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  • 1
    Electronic Resource
    Electronic Resource
    Hyperbolic automorphisms of free groups (2000)
    Springer
    Geometric and functional analysis 10 (2000), S. 1071-1089 
    Details
    ISSN: 1420-8970
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. We prove that an automorphism $ {\not o} : F \to F $ of a finitely generated free group F is hyperbolic in the sense of Gromov if it has no nontrivial periodic conjugacy classes. This result was previously claimed (but not proved) in [BF1].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00001647
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Detection of Rare Earth Elements in Minerals and Soils by Laser-Induced Breakdown Spectroscopy (LIBS) Using Interval PLS (2021)
    In:  Minerals
    Details
    Publication Date: 2021-12-08
    Description: The numerous applications of rare earth elements (REE) has lead to a growing global demand and to the search for new REE deposits. One promising technique for exploration of these deposits is laser-induced breakdown spectroscopy (LIBS). Among a number of advantages of the technique is the possibility to perform on-site measurements without sample preparation. Since the exploration of a deposit is based on the analysis of various geological compartments of the surrounding area, REE-bearing rock and soil samples were analyzed in this work. The field samples are from three European REE deposits in Sweden and Norway. The focus is on the REE cerium, lanthanum, neodymium and yttrium. Two different approaches of data analysis were used for the evaluation. The first approach is univariate regression (UVR). While this approach was successful for the analysis of synthetic REE samples, the quantitative analysis of field samples from different sites was influenced by matrix effects. Principal component analysis (PCA) can be used to determine the origin of the samples from the three deposits. The second approach is based on multivariate regression methods, in particular interval PLS (iPLS) regression. In comparison to UVR, this method is better suited for the determination of REE contents in heterogeneous field samples
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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    PAPER (OA)
  • 3
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    Comparison of Handheld and Echelle Spectrometer to Assess Copper in Ores by Means of Laser-Induced Breakdown Spectroscopy (LIBS) (2023)
    In:  Minerals
    Details
    Publication Date: 2023-04-18
    Description: Its properties make copper one of the world’s most important functional metals. Numerous megatrends are increasing the demand for copper. This requires the prospection and exploration of new deposits, as well as the monitoring of copper quality in the various production steps. A promising technique to perform these tasks is Laser Induced Breakdown Spectroscopy (LIBS). Its unique feature, among others, is the ability to measure on site without sample collection and preparation. In this work, copper-bearing minerals from two different deposits are studied. The first set of field samples come from a volcanogenic massive sulfide (VMS) deposit, the second part from a stratiform sedimentary copper (SSC) deposit. Different approaches are used to analyze the data. First, univariate regression (UVR) is used. However, due to the strong influence of matrix effects, this is not suitable for the quantitative analysis of copper grades. Second, the multivariate method of partial least squares regression (PLSR) is used, which is more suitable for quantification. In addition, the effects of the surrounding matrices on the LIBS data are characterized by principal component analysis (PCA), alternative regression methods to PLSR are tested and the PLSR calibration is validated using field samples.
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 4
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    Gene-expression profiling of HIV-1 infection and perinatal transmission in Botswana (2006)
    Springer Nature
    Details
    Publication Date: 2006-05-04
    Print ISSN: 1466-4879
    Electronic ISSN: 1476-5470
    Topics: Biology , Medicine
    Published by Springer Nature
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    PAPER CURRENT
  • 5
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    Main characteristics of the Large Space Simulation (LSS) (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The large space simulator at its European space research and technology center (ESTEC) was implemented. The facility enables mechanical and thermal tests on large satellites. The chamber will be equipped with a collimated solar beam of 6 meter diameter. Infrared equipment is available as alternative or complementary source of thermal radiation. Controlled variation of shroud temperatures can be utilized for thermal testing or temperature cycling of hardware. The basic concept and major design aspects of the facility are presented.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: NASA. Goddard Space Flight Center 13th Space Simulation Conf.; p 30-51
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Environmental test facilities used in Europe for ESA satellite programmes (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The structure of the European Space Agency (ESA) is described. The major test facilities used for ESA programs are described. Facility characteristics and special test methods are described.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA. Goddard Space Flight Center 12th Space Simulation Conf.; 28 p
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    HYDRA, a new tool for mechanical testing (1994)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The introduction outlines the verification concept for programs of the European Space Agency (ESA). The role of the Agency in coordinating the activities of major European space test centers is summarized. Major test facilities of the environmental test center at ESTEC, the Space Research and Technology Center of ESA, are shown and their specific characteristics are highlighted with special emphasis on the 6-degree-of-freedom (6-DOF) hydraulic shaker. The specified performance characteristics for sine and transient tests are presented. Results of single-axis hardware tests and 6-DOF computer simulations are included. Efforts employed to protect payloads against accidental damage in case of malfunctions of the facility are listed. Finally the operational advantages of the facility, as well as the possible use of the HYDRA control system design for future applications are indicated.
    Keywords: GROUND SUPPORT SYSTEMS AND FACILITIES (SPACE)
    Type: NASA. Goddard Space Flight Center, Eighteenth Space Simulation Conference: Space Mission Success Through Testing; p 299-312
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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