A method of deriving a conclusion of the condition of slurry flow in a non-vertical conduit includes artificially generating a first locally heated spot on an interior surface of the conduit at the invert of the conduit and artificially generating a second locally heated spot on the interior surface of the conduit at a location angularly spaced from the first heated spot at an angular spacing of at least 90. The temperatures of the heated spots are measured, obtaining first and second temperature values T1, T2. Electronically generated signals carrying the values T1, T2 are communicated to an electronic computing device. The computing device automatically calculates a first temperature difference T1 minus T2 and automatically derives a conclusion of the condition of slurry flow prevailing in the conduit based on the relationship between the value of the first temperature difference and a first reference parameter.

There is provided a fall detector for detecting falls of a user or an object to which the fall detector is attached, characterized in that the fall detector comprises an air flow sensor for providing measurements indicative of vertical velocity and/or changes in altitude of the fall detector.

A nebulizer comprises a head detachably coupled to a body. The head comprises a nebulizer, an air channel and a flow sensor. A nebulized liquid is released in an air channel that ends in a mouth piece through which a user inhales and exhales. The inhaling and exhaling causes a flow in the air channel which is detected with the flow sensor. The nebulizer is controlled by a controller included in the body.

A wind direction meter has the following plurality of sensors and a control unit. Each sensor has a first surface and has first and second interlayer connection members made of different metals or semiconductors. Further, the wind direction meter includes a thermoelectric conversion element which generates an electrical output when a temperature difference occurs between first ends and second ends of the respective first and second interlayer connection members. The sensor generates an electric output when the surrounding air, whose temperature has been changed by a heater, is moved by the wind to produce a temperature difference between the first ends and the second ends of the first and second interlayer connection members. The control unit calculates the direction of the wind on the basis of the difference in output. Thus, the wind direction of a weak wind can be detected with the wind direction meter.