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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 28 (1970), S. 135-154 
    ISSN: 1439-6327
    Keywords: Work above the Head ; Maximum Working Time ; Endurance Limits ; Rest Allowances ; Überkopfarbeit ; Maximale Arbeitszeit ; Dauerleistungsgrenzen ; Erholungszuschläge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 4 weibliche und 6 männliche Versuchspersonen leisteten an einem Handergometer pausenlose Arbeit mit den Handmuskeln bei Leistungen von 0,1–1,2 mkp/sec, während die Hände verschieden weit über Herzhöhe erhoben waren. Es wurden maximale Arbeitszeit, Pulsfrequenz und Energieumsatz bestimmt. Bei gleicher Leistung war die maximal mögliche Arbeitszeit um so kürzer, je höher die Arbeitsposition der Hände war. Gleichzeitig ergab sich ein steilerer Anstieg der Pulsfrequenz während der Arbeit. Bedingt durch die Arbeit des Hochhaltens der Arme nahm die Sauerstoffaufnahme bei gleicher Arbeit zu, so daß sich der Wirkungsgrad von etwa 13% in Herzhöhe auf ungefähr 2% bei maximalem Hochhalten der Hände verringerte. Die vermutlichen Ursachen des Einflusses der Arbeitsposition auf die Leistungsfähigkeit werden diskutiert. Ebenso wie die maximale Leistungsfähigkeit verringerte sich auch die Dauerleistungsfähigkeit mit zunehmender Höhe der arbeitenden Hände. In Versuchen mit Arbeitspausen wurde für einige Leistungen die Größe der Erholungszuschläge ermittelt, die für verschiedene Arbeitspositionen notwendig waren.
    Notes: Summary 4 female and 6 male test subjects performed continuous work by their hand muscles while their hands were elevated in different positions above heart level. The output of the ergometer especially built for this purpose was changed between 0.1 and 1.2 mkp/sec. Metabolic rate, heart rate, and maximum working time were measured. At constant ergometer output maximum working time decreased with increasing elevation of hands. Simultaneously heart rate increase during work became faster. Oxygen consumption during equal ergometer output increased with increasing elevation of hands so that mechanical efficiency decreased from about 13% (work at heart level) to 2% (maximum elevation). Possible reasons of the influence of various working positions on performance are discussed. As well as maximum working capacity did endurance limit decrease with increasing elevation of working hands. In experiments with intermittant work rest allowances required for various working positions were evaluated.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 20 (1999), S. 229-235 
    ISSN: 1572-9567
    Keywords: Joule–Thomson inversion curves ; Lennard–Jones fluid ; molecular simulations ; Monte Carlo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method to determine Joule–Thomson inversion curves, using isobaric-isothermal Monte Carlo molecular simulations, is presented. The usual experimental practice to obtain the locus of points in which the isenthalpic derivative of temperature with respect to pressure vanishes is to process volumetric data by means of thermodynamic relations. This experimental procedure requires the very precise measurement of volumetric properties at conditions up to five times the fluid's critical temperature and twelve times its critical pressure. These harsh experimental conditions have hindered the publication of data for even simple fluids and mixtures. By using molecular simulation, these problems may be circumvented, since the computational effort is roughly independent of the actual value of the pressure or the temperature. In general, Joule–Thomson inversion curves obtained by molecular simulation may be used either as an unambiguous test for equations of state in the supercritical and high-pressure regions or for the prediction of real fluid behavior, should the potential be well known. Both applications are exemplified for a Lennard-Jones fluid for which the complete inversion curve is obtained.
    Type of Medium: Electronic Resource
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