Abstract: The invention relates to a method for measuring gas content in a fluid, such as papermaking pulp or coating paste, and to a gas content measuring device. Pressure variations generated by a pump, for instance, are to occur in the fluid. Travel time, phase and/or attenuation of the microwave signal (20) are measured with the gas content measuring device while the signal (20) penetrates through the fluid (13), and the gas content is determined on the basis of changes in travel time, phase and/or attenuation of the microwave signal (20) caused by pressure variations of the fluid (13).

Abstract: A flow meter for measuring the flow in a dielectric pipe is disclosed. Two microwave signals are transmitted at measurement points via at least two transmitter antennae through the dielectric pipe and a flowing material. The distance between the measurement points is known. The signals that have passed through are received by receiver antennae and signal cross correlation is formed by a correlator, the flow rate being determined on the basis of the best correlation result. The measurement result is improved by filtering and/or directing the signals.

Abstract: The invention relates to a method and apparatus for measuring and controlling optical properties of a moving web. Sensor heads are installed in the same location on the opposite sides of the web to be measured so that there is at least one means of illuminating the web and at least one means of detecting radiances on both sides of the web. At least one means of illuminating the web of at least one side is controlled so as to provide at least two different lighting states. Measuring the values in different lighting states with both means of detecting radiances simultaneously allows determination the optical properties of the web on its both sides.

Abstract: Method for operating a traversing sensor apparatus, wherein the properties of a paper web are measured through traversing such that a measuring head is moved during the measurement in the cross-machine direction. The movement of the measuring head in the cross-machine direction is stopped above the paper web and data is collected for a certain period through measurement from an area narrower than the width of the paper web, whereafter the movement of the measuring head in the cross-machine direction is continued. The data collected from an area narrower than the width of the paper web is used to calculate MD and CD values and to determine the effect of harmonic variations.

Abstract: The invention relates to a method and an equipment for defining the cross-directional properties of a sheet in a continuous sheet making process. According to the invention, the set point profile of the actuators affecting the cross-directional properties of the sheet is defined, high frequencies are filtered from the defined profile, and shrinkage nonlinearity is deduced from the filtered profile without modulating or stimulating the actuators.