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Träfflista för sökning "LAR1:hh srt2:(1995-1999);pers:(Malmqvist L.)"

Sökning: LAR1:hh > (1995-1999) > Malmqvist L.

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1.
  • Carlsson, J., et al. (författare)
  • Application of optical fluorescence spectroscopy to paper production
  • 1999
  • Ingår i: TAPPI INTERNATIONAL PAPER PHYSICS CONFERENCE. - Atlanta : Tappi Press. - 0898529549 ; , s. 429-436
  • Konferensbidrag (refereegranskat)abstract
    • Fluorescence light emitted from paper following the absorption of either ultraviolet or visible light has a wavelength distribution determined by the chemical composition of the paper. This can be used both for laboratory measurements of paper characteristics and for on-line monitoring of the paper during production. Such measurements can be performed non-intrusively at sampling rates high enough to give a sub-millimetre resolution in the machine direction in a paper machine or rerewinder. In this project two types of fluorescence monitors have been constructed. They are operating at different wavelengths and thereby they monitor different substances in the paper. The monitors have been tested at newsprint producing paper mills together with an optical speedometer. The measurements in the production environment have shown that the equipment is capable of indirectly monitoring paper quality parameters which affect the local abundance of lignin. Examples of such parameters are the number of shives in the paper and wire marks. A fluorescence based method for scanning cross-directional newsprint profiles in the laboratory has been developed. From these measurements the relative shrinkage of the paper during drying can be calculated using time-frequency analysis.
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2.
  • Kristiansson, P., et al. (författare)
  • Optical dot gain on newsprint determined with the Lund nuclear microprobe
  • 1997
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - Amsterdam : Elsevier. - 0168-583X .- 1872-9584. ; 130:1-4, s. 303-307
  • Tidskriftsartikel (refereegranskat)abstract
    • A technique for measuring optical dot gain, i.e. the relative difference between the actual screen dot and the optically perceived one, is presented. By combining measurements from the non-optical nuclear microprobe with data from image analyzing technique the optical dot gain can be determined. The procedure to reach pixel by pixel correlation on a micrometer scale is discussed. In the newsprint sample studied in this investigation a typical optical dot gain between 15 and 20% was deduced. The variation in the optical dot gain was correlated with other characteristic parameters of the print and newsprint and especially a positive correlation to the mass density of the newsprint was observed. (C) 1997 Elsevier Science Ltd.
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4.
  • Verikas, Antanas, 1951-, et al. (författare)
  • A New method for colour measurements in graphic arts
  • 1999
  • Ingår i: Color Research and Application. - New York : Wiley-Blackwell. - 0361-2317 .- 1520-6378. ; 24:3, s. 185-196
  • Tidskriftsartikel (refereegranskat)abstract
    • This article presents a method for colour measurements directly on printed half-tone multicoloured pictures. The article introduces the concept of colour impression. By this concept we mean the CMY or CMYK vector (colour vector), which lives in the three- or four-dimensional space of printing inks. Two factors contribute to values of the vector components, namely, the percentage of the area covered by cyan, magenta, yellow, and black inks (tonal values) and ink densities. The colour vector expresses integrated information about the tonal values and ink densities. Values of the colour vector components increase if tonal values or ink densities rise and vice versa. If, for some primary colour, the ink density and tonal value do not change, the corresponding component of the colour vector remains constant. If some reference values of the colour vector components are set from a preprint, then, after an appropriate calibration, the colour vector directly shows how much the operator needs to raise or lower the cyan, magenta, yellow, and black ink densities in order to correct colours of the picture being measured. The values of the components are obtained by registering the RGB image from the measuring area and then transforming the set of registered RGB values to the triplet or quadruple of CMY or CMYK values, respectively. Algorithms based on artificial neural networks are used for performing the transformation. During the experimental investigations, we have found a good correlation between components of the colour vector and ink densities.
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  • Resultat 1-4 av 4

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