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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 1962-1971 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design and performance of a new high-speed imaging spectrometer system developed for the spectral analysis of micrometer-sized features in transmitted light. The instrument utilizes the wavelength range from ultraviolet (UV) to near infrared (NIR) (250–975 nm). The extension into the ultraviolet range is to our knowledge unique. The system comprises two white light sources (xenon and halogen lamps), a motorized sample stage, microscope optics with slit-determined field of view, and three (UV, visible and NIR) parallel optical recording channels. The dispersive optical recording system is based on holographic gratings and uses charge-coupled-device (CCD) cameras as imaging detectors. The instrument has been fully integrated with data acquisition and control systems. Subsequent data analysis is performed by dedicated software. The instrument provides spectral images from narrow wavelength bands (5 nm). In such an image the spectral information from a selected wavelength band is depicted with its corresponding geometric location, i.e., a single pixel on the CCD chip. Hence, objects can be visualized in different wavelength bands and a spectrum can easily be produced for each location of the object. The instrument can measure objects up to 900 μm×27 mm with a spectral resolution better than 5 nm and a spatial resolution better than 5 μm. The imaging spectrometer system provides a powerful combination of spectroscopy and image processing for use in many applications in research, control and quality assessment, where spectral information and its location are of interest. Although the system has been primarily developed for applications in the pulp and paper industry, it has a vast potential for spectroscopic analysis with a micrometer spatial resolution in general and for measurements of impurities and their locations in products in particular. As an example of a measurement, spectral image data from a wood fiber are presented. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 47 (1975), S. 855-860 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Designs, codes and cryptography 4 (1994), S. 69-81 
    ISSN: 1573-7586
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We consider the authentication problem, using the model described by Simmons. Several codes have been constructed using combinatorial designs and finite geometries. We introduce a new way of constructing authentication codes using LFSR-sequences. A central part of the construction is an encoding matrix derived from these LFSR-sequences. Necessary criteria for this matrix in order to give authentication codes that provides protection aginst impersonation and substitution attacks will be given. These codes also provide perfect secrecy if the source states have a uniform distribution. Moreover, the codes give a natural splitting of the key into two parts, one part used aginst impersonation attacks and a second part used against substitution attacks and for secrecy simultaneously. Since the construction is based on the theory of LFSR-sequences it is very suitable for implementation and a simple implementation of the construction is given.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Designs, codes and cryptography 6 (1995), S. 205-218 
    ISSN: 1573-7586
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper we introduce a new way of constructingA 2-codes, i.e., authentication codes that protect against deceptions from an opponent and additionally also protect against deceptions from the transmitter and the receiver. The construction uses codes for the rank metric, a well-known field in coding theory. The construction gives improved performance compared with previous work and it also gives an opportunity to use unequal authentication protection when the participants are unequally trusted.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2233-2238 
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Fluorescence ; UV detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A new method for investigation of axial-beam absorption detection for improved detection limits in microcolumn separations is reported. The method is based on fluorescence imaging of light absorption along a separation capillary. The probing UV light is introduced at one end of the capillary and shows an exponential fall-off along the capillary. As the UV light propagates through the sample peaks, an additional loss in intensity will be observed. In order to view the absorption profile along the capillary, a background fluorophore is added to the buffer. A charge-coupled device (CCD) detector and imaging optics are placed beside the capillary to view the capillary in a direction perpendicular to the capillary. Signal integration is employed for consecutive exposures as well as for neighboring detector pixels in order to increase the signal-to-noise ratio. Measurements for stilbene 3 with sulforhodamine B as a background fluorophore are presented. The characteristics of the detection method and potential improvements are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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