CD variations and/or MD variations in scan measurements are determined from spectral components of power spectra of scan measurements taken using two or more scanning speeds. Dominant spectral components having the same spatial frequencies identify CD variations and dominant spectral components having the same temporal frequencies identify MD variations. Dominant spectral components are extracted from a noisy power spectrum (PS) by sorting all spectral components into an ordered PS. A first polynomial representing background noise of the ordered PS is used to set a first threshold. Spectral components of the ordered PS that exceed the first threshold are removed to form a noise PS. A second polynomial representing the noise PS is used to set a second threshold. Spectral components of the PS that exceed the second threshold are identified as dominant spectral components of the PS.

A paper management system setting a paper information piece of paper stored in a sheet feeding unit in an image forming apparatus from a list of paper information pieces registers the paper information pieces with a favorite group, displays a list of the paper information pieces for each favorite group, and enables the list of the paper information pieces to be associated with a paper feed unit through the screen displaying the list.

An inspection device of the present invention includes: THz wave irradiation unit for irradiating a specimen with THz waves; a THz wave sensing unit for detecting transmitted waves or reflected waves of the THz waves emitted to the specimen; and an information processing unit for acquiring intensity distribution of the transmitted waves of the reflected waves of the specimen from the intensity data of the transmitted waves or the reflected waves of the specimen irradiated with the THz waves, wherein the information processing unit acquires 2-dimensional intensity distribution of the transmitted waves or reflected waves, and detects whether a foreign matter is adhering to the specimen by comparing the intensity distribution obtained when the specimen without attachment of the foreign matter is detected and the intensity distribution obtained when the specimen is detected at the time of inspection. The specimen is a sheet of paper, for example.

An approximation B′f(Id,λ) of a fluorescence spectral emissivity coefficient by a standard illumination light Id is obtained at following steps from spectral power distributions R(Ik,λ) of sample radiation lights radiated from a fluorescence whitened sample when the fluorescence whitened sample is sequentially illuminated with a plurality of excitation lights Ik having different spectral power distributions, and a spectral power distribution Id(λ) of the standard illumination light Id. Spectral power distributions Rf(Ik,λ) of fluorescence are obtained from the spectral power distributions R(Ik,λ) by respective excitation lights Ik (first step). The spectral power distributions Rf(Ik,λ) of fluorescence by the respective excitation lights Ik are linearly combined with a given weighting coefficient Wk, and an approximation R′f(Id,λ) of a spectral power distribution of fluorescence by the standard illumination light Id is obtained by equation (second step: #11). From the approximation R′f(Id,λ) and the spectral power distribution Id(λ) of the standard illumination light Id, the approximation B′f(Id,λ) is obtained by equation (third step: #12).

The present invention relates to a method of determining the moisture content of a web of cellulose pulp arriving at a pulp dryer. The method comprises measuring, at several instants during a predetermined time interval, the moisture content of said web using a moisture sensor arranged upstream of the pulp dryer; measuring state variables of drying medium of said pulp dryer; calculating, based on said moisture sensor measurements, a total value of moisture introduced into the pulp dryer by a portion of said web during said predetermined time interval; determining, based on said measured state variables, a predicted total value of moisture present inside the pulp dryer; comparing said calculated total value with said predicted total value to obtain a deviation therebetween; calibrating said moisture sensor using said deviation; and measuring the moisture content of a web of cellulose pulp using said calibrated moisture sensor.

Methods of characterizing the topography of a surface of a creped material, devices for characterizing surface topography of a creped material, computer systems for characterizing surface topography of a creped material, and the like, are disclosed.

The invention relates to a method and arrangement for detecting free fiber ends in a paper surface. The method comprises illuminating a target sample (6) surface, which comprises free fiber ends, from at least two directions one at the time, with at least one light source (1). Original reflectance images are obtained for the target sample (6) surface with an imaging device (4), and a surface normal is estimated for each image pixel of the original reflectance image. Thus it is possible to reconstruct a reconstructed reflectance image from the estimated surface normals, and to compare the reconstructed reflectance image and the corresponding original reflectance image and to construct a difference image, where the differences represent shadow objects of the free fiber ends in a paper surface.

A method includes, using at least one processing device, obtaining position measurements and/or tilt angle measurements associated with a tissue web and identifying a stretch measurement associated with the tissue web using the obtained measurements. Identifying the stretch measurement could include using one or more mathematical formulas to calculate the stretch measurement associated with the tissue web using the obtained measurements. The one or more mathematical formulas could be defined using laboratory stretch values of multiple training webs. Different mathematical formulas can be associated with training webs having different characteristics, and the method may further include selecting at least one of the mathematical formulas based on one or more characteristics of the tissue web.

An apparatus adapted to examine a paper web includes a rotatable first bobbin, a rotatable second bobbin, and a first testing device. The first bobbin has a paper we wound thereabout that has transverse bands spaced apart along a length thereof. The second bobbin is arranged to receive the paper web from the first bobbin with a paper web path defined between the first and second bobbins. The first testing device is disposed along the paper web path and is arranged to nondestructively measure a diffusivity of one of the transverse bands of the paper web.

A method of measuring properties of a moving cellulose, paper or board sheet. A first parameter of a first resonance caused by the moving sheet in a frequency range 1 GHz to 25 GHz of electromagnetic radiation is measured. A second parameter of an electromagnetic signal transmitted between at least a pair of transceiver parts of a transceiver sensor located on opposite sides of the moving sheet through the moving sheet is measured in a frequency range 25 GHz to 1000 GHz. A minimum difference between the frequency ranges related to the first parameter and the second parameter being at least 5 GHz. Both the dry stuff content and the weight of water per unit of area are determined on the basis of the first parameter, the second parameter and available information related to a distance travelled by the electromagnetic signal.