Abstract: The present invention provides a method and apparatus for identifying deformation of a moving sheet. In the present invention, the periodicity of original periodic or nearly periodic markings initially caused on the sheet is determined. Thereafter, a Fourier image of periodic markings of the sheet as it is moved along a path is produced with an imaging device using a Fourier transform optical element. The appropriate peaks of the Fourier image corresponding to the markings of the sheet are located, and the deformation of the sheet is calculated by comparing the measured peaks of the Fourier image to the known initial periodicity of the markings.

Abstract: The invention relates to an apparatus for measuring properties of a moving paper web or cardboard web. The apparatus comprises a sensor and a counterpart. The sensor comprises at least one coil. The sensor is arranged on a first side of the moving web and the counterpart is arranged on a second side of the moving web. The coil comprises a plurality of layers, each layer constituting a part of the coil, the layers being superimposed and coupled in series to constitute the coil.

Abstract: The invention relates to a method and an apparatus for controlling a coloring process. In the coloring process, at least one fluorescent or non-fluorescent ingredient is added and the color of the substrate is determined by using a coloring model which describes the effect of said ingredient on the radiance transfer factor for the substrate to be colored.

Abstract: The invention relates to a method and an apparatus for measuring properties of a moving web, a sensor (1) being arranged on a first side of the moving web (7), the sensor comprising a differential coil (3), which comprises at least two coils, and a reference plate (4). A sensor plate (6) is arranged on a second side of the moving web (7). Electric current is used to induce a voltage to the differential coil (3). The voltage of the differential coil (3) varies as the web (7) changes the effect caused by the sensor plate (6) to the differential coil. The properties of the web (7) are determined by measuring the voltage of the differential coil (3).

Abstract: The invention relates to a method and equipment for controlling properties of paper, in which method the effect of the flow of retention agent (Fra) and the stock flow (Fts) on the basis weight of the paper (BW) is modelled. The fulfilled modelling is used to adjust the basis weight of the paper (BW) by controlling simultaneously the flow of retention agent (Fra) and the stock flow (Fts).

Abstract: The invention relates to a method and equipment for controlling properties of paper, which method comprises modelling the effect of the flow of retention agent (Fra) both on the amount of filler in the white water and on the paper ash content (ASH), and the effect of the flow of filler (Ffi) both on the paper ash content (ASH) and on the amount of filler in the white water. The fulfilled modelling is used to adjust the amount of filler in the white water and the paper ash content (ASH) by controlling simultaneously the flow of retention agent (Fra) and the flow of filler (Ffi).

Abstract: A method for blowing steam against a paper web, whereby the steam is blown by a steam box having several profiling chambers in the cross direction of a paper machine. The cross-profile of the paper web is controlled by means of the steam supplied by the profiling chambers. A gas flow is provided between the profiling chambers to prevent the steam blown by a profiling chamber from affecting the effective area of the steam blown by the adjacent profiling chamber. Further, a steam box for implementing the method is disclosed.

Abstract: The invention relates to a method and an apparatus for defining the position of an actuator. The position of the actuator (1) is measured by a measuring signal (3) proportional to the rotation of a shaft (6) of the actuator (1). The measuring signal (3) comprises successive pulses. The intervals between the pulses are divided into parts, and the position of the actuator (1) between the pulses is defined utilizing the parts of the divided pulse intervals.

Abstract: The invention relates to a method and apparatus for measuring paper color. Paper color is measured from the surface of a paper roll on a winder.

Abstract: The invention relates to a method and apparatus for determining the color and/or composition of a material. A sample of the material is illuminated with at least three separate illumination bands singly or in combination, said illumination bands collectively substantially spanning at least the visible range. The light reflected or transmitted by the sample is measured with at least four light detector elements responsive to light in wavelength bands which substantially span the visible range when the sample is illuminated. The width of the illumination bands differs in such a manner that the illumination bands are narrowest near the expected fluorescence absorption bands.

Abstract: The invention relates to a method and apparatus for measuring the caliper of paper substantially continuously during papermaking. A sensor (3a, 3b) is arranged above and/or under the paper (2), the sensor (3a, 3b) measuring the caliper of the paper (2) at least on one side of the paper (2) mainly without contacting the surface of the paper (2). At given intervals the sensor (3a, 3b) measuring mainly without contact is brought into momentary contact with the surface of the paper (2).

Abstract: The invention relates to a method for positioning an actuator. In the method, the actuator is controlled by a continuous control pulse (2a) toward a desired value (1), and the position of the actuator is measured. Further, a pulsing range limit located before the desired value (1) is defined, and when the position of the actuator is past the pulsing range limit (3), the motion of the actuator is stopped. The pulsing range limit (3) is defined to be so far from the desired value (1) that the actuator stops before its position is substantially past the desired value (1). The position of the actuator is then measured, and if necessary, a corrective run is performed.

Abstract: The invention relates to a method and apparatus for determining the color and/or composition of a material. A sample of the material is illuminated with at least three illumination bands singly or in combination, said illumination bands collectively substantially spanning at least the visible range. The light reflected or transmitted by the sample is measured with at least four light detector elements responsive to light in wavelength bands which substantially span the visible range when the sample is illuminated. The measured reflected or transmitted light is compared to the light reflected or transmitted by a reference material of known apparent emissivity or transmissivity and the apparent emissivity or transmissivity of the sample is calculated therefrom.