The subject matter of this specification can be embodied in, among other things, a method of sensing that includes measuring an acoustic impedance of a fluid, measuring a first time of flight in a first direction through the fluid, measuring a second time of flight in a second direction through the fluid, determining a mass fluid flow rate based on the measured acoustic impedance, the measured first time of flight, and the measured second time of flight, and providing the determined mass fluid flow rate.

An apparatus for measuring a parameter of a fluid flow passing within a pipe is provided. The apparatus includes a sensing device and a processing unit. The sensing device has a sensor array that includes at least one first macro fiber composite (MFC) strain sensor disposed at a first axial position, and at least one second MFC strain sensor disposed at a second axial position. The first axial position and the second axial position are spaced apart from one another. The at least one first MFC strain sensor and the at least one second MFC strain sensor are both configured to produce signals representative of pressure variations of the fluid flow passing within the pipe. The processing unit is configured to receive the signals from the sensor array and measure one or more fluid flow parameters based on the signals.

An apparatus for measuring a parameter of a fluid flow passing within a pipe is provided. The apparatus includes a sensing device and a processing unit. The sensing device has a sensor array that includes at least one first macro fiber composite (MFC) strain sensor disposed at a first axial position, and at least one second MFC strain sensor disposed at a second axial position. The first axial position and the second axial position are spaced apart from one another. The at least one first MFC strain sensor and the at least one second MFC strain sensor are both configured to produce signals representative of pressure variations of the fluid flow passing within the pipe. The processing unit is configured to receive the signals from the sensor array and measure one or more fluid flow parameters based on the signals.

An aircraft includes an engine, a fuel tank, a chamber, a system, and an introduction line. The chamber is located in the tank, occupies only a part of the tank, and includes a sensor for measuring a property of the fuel. The system injects fuel into the line. The introduction line introduces fuel from the injection system into the chamber. The introduction line includes a valve capable of preventing an introduction of fuel from the injection system into the chamber via the line.

Mass flow verification systems and apparatus may verify mass flow rates of mass flow controllers (MFCs) based on choked flow principles. These systems and apparatus may include a plurality of differently-sized flow restrictors coupled in parallel. A wide range of flow rates may be verified via selection of a flow path through one of the flow restrictors based on an MFC's set point. Mass flow rates may be determined via pressure and temperature measurements upstream of the flow restrictors under choked flow conditions. Methods of verifying a mass flow rate based on choked flow principles are also provided, as are other aspects.

The invention relates to a method and to an arrangement for feeding fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2). The invention relates also to a controlling means for controlling feeding of fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2) in an arrangement for feeding fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2). The invention relates also to controlling means for controlling feeding of fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2) in an arrangement for feeding fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2) and to a computer program product.

The invention relates to a method and to an arrangement for feeding fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2). The invention relates also to a controlling means for controlling feeding of fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2) in an arrangement for feeding fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2). The invention relates also to controlling means for controlling feeding of fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2) in an arrangement for feeding fine-grained matter to a concentrate burner (1) or a matte burner of a suspension smelting furnace (2) and to a computer program product.

On board an aircraft, a method is perform in which the following steps are implemented in the following order: measuring a first density value, a first dielectric constant value and a first temperature value of the fuel at a first time, measuring a second density value, a second dielectric constant value and a second temperature value of the fuel, determining parameters of a function for calculating a density from a temperature or a dielectric constant, measuring a volume flow rate value and at least one of a third temperature value and a third dielectric constant value of the fuel in a fuel injection duct in the engine, and determining a density value of the fuel and a mass flow rate of the fuel in the injection line.

On board an aircraft, a method is perform in which the following steps are implemented in the following order: measuring a first density value, a first dielectric constant value and a first temperature value of the fuel at a first time, measuring a second density value, a second dielectric constant value and a second temperature value of the fuel, determining parameters of a function for calculating a density from a temperature or a dielectric constant, measuring a volume flow rate value and at least one of a third temperature value and a third dielectric constant value of the fuel in a fuel injection duct in the engine, and determining a density value of the fuel and a mass flow rate of the fuel in the injection line.

A dry bulk pneumatic metering system includes a flow line configured for the passage of pneumatically-conveyed bulk material, a bulk material sensor arranged relative to the flow line, the bulk material sensor configured to send a first signal related to a quantity of the bulk material passing in the flow line and within a range of the bulk material sensor, a speed sensor arranged with respect to at least one area of the system, the speed sensor configured to send a second signal related to the speed of gas flow at the at least one area of the system, and a controller arranged to receive the first and second signals and configured to calculate a bulk material flow rate of the bulk material using the first and second signals.