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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 15 (1986), S. 135-141 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Introductory investigations performed in order to make quantitative electron-probe microanalysis of very light elements such as boron, carbon, nitrogen or oxygen possible are described. The practical problems encountered in this kind of work are discussed in detail and, where possible, solutions are proposed. It is shown that with very light elements such as carbon it is no longer permitted to measure x-ray intensities at the position of the maximum of the emission peak as the shape of the carbon Kα peak is subject to strong alterations, depending on the type of chemical bond involved. As a consequence, integral measurements have to be performed and it is shown that errors of 30-50% can easily be made if this is neglected. The lengthy procedures, connected with integral intensity measurements, can be shortened considerably by the introduction of area/peak factors, which, by definition, represent the ratio between the correct area (integral) and the peak intensity ratio. The accurate determination of such factors for 13 binary carbides is described. This set of factors will permit future measurements simply on the peak; multiplication of the peak intensity ratio by the appropriate area/peak factors will then yield the correct integral intensity ratios.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 13 (1984), S. 91-97 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A computer program based on the use of Gaussian expressions for the x-ray distribution with depth [φ(ρz)curves] was tested on its usefulness for quantitative electron probe microanalysis. As the good results originally claimed for a similar program could not be reproduced initially, it was subjected to a detailed analysis. As a result, some modifications in the approach are proposed. Apart from increasing the speed of calculation considerably, the modified expressions provide a better insight into the delicate balance which has to exit between the relevant quantities involved. After a new optimization process the modified program was tested on about 450 published microanalyses. The results show that the φ(ρz) approach is indeed very promising as a narrow histogram with an r. m. s. value of 5. 4% could be produced. Finally, some suggestions are made for future improvements.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 15 (1986), S. 143-150 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The performances of four current matrix correction programs have been tested on a data file of measurements on 13 binary carbides between 4 and 30 kV. Both the metal lines as well as the carbon Kα line have been measured, which resulted in 145 k ratios for the metals (relative to elemental standards) and 117 integral k ratios for carbon Kα (relative to Fe3C).Evidence is presented that the existing sets of mass absorption coefficients for carbon Kα radiation are perhaps not fully consistent and a new set is therefore proposed, which is in better agreement with the experimental results. Finally, it is shown that the modified Gaussian φ(ρz) approach, when used in conjunction with the new set of mass absorption coefficients, leads to unexpectedly good results, with a relative root-mean-square value of 3.7%. This demonstrates that even for carbon very good accuracy can be obtained, provided that proper care is exercised in the measurements and the proper procedures are followed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
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    In:  CASI
    Publication Date: 2013-08-31
    Description: Viewgraphs on vibration isolation are presented. Techniques to control and isolate centrifuge disturbances were identified. Topics covered include: disturbance sources in the microgravity environment; microgravity assessment criteria; life sciences centrifuge; flight support equipment for launch; active vibration isolation system; active balancing system; and fuzzy logic control.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: Workshop on Fuzzy Control Systems and Space Station Applications; p 435-443
    Format: application/pdf
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  • 5
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2013-08-31
    Description: Viewgraphs on rotational speed control are presented. The Centrifuge Facility Systems Study - 2.5 m centrifuge is shown. A life sciences centrifuge is scheduled to fly aboard Space Station Freedom. Live animal and plant specimens will be carried on the rotor and compared with microgravity specimens in racks.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: Workshop on Fuzzy Control Systems and Space Station Applications; p 427-434
    Format: application/pdf
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  • 6
    facet.materialart.
    Unknown
    In:  CASI
    Publication Date: 2019-06-28
    Description: Design concepts for improved fecal waste collection both on the space shuttle orbiter and as a precursor for the space station are discussed. Inflight usage problems associated with the existing orbiter waste collection subsystem are considered. A basis was sought for the selection of an optimum waste collection system concept which may ultimately result in the development of an orbiter flight test article for concept verification and subsequent production of new flight hardware. Two concepts were selected for orbiter and are shown in detail. Additionally, one concept selected for application to the space station is presented.
    Keywords: MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT
    Type: NASA-CR-171830 , NAS 1.26:171830 , MDC-H1360
    Format: application/pdf
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