1,721,017 research outputs found
Su di una tecnica di adeguamento delle pompe centrifughe a mutate esigenze impiantistiche
No full textRicostruzionre tridimensionale mediante le inverse generalizzate a mezzo degli autovettori ed autovalori
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Su di una tecnica di adeguamento delle pompe centrifughe a mutate esigenze impiantistiche
No full textCondizioni di affaticamento per la barra di accoppiamento degli elettrotreni ET100 in servizio SEPSA
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A Rheological Investigation of the Crystallization Kinetics of Syndiotactic Polypropylene of Varying Degree of Tacticity
No full textThe crystallization behavior of five Syndiotactic Polypropylene (sPP) samples of varying degree of tacticity has been studied by means of rheological techniques and compared to the results of more standard DSC measurements. Small Amplitude Oscillatory Shear (SAOS) measurements have been performed on a controlled stress rotational rheometer equipped with a nitrogen-fed, forced convection oven, which allows for good temperature stability and relatively high heating/cooling rates. Both non-isothermal and isothermal crystallization tests have been carried out. The former proved useful to determine the melting and crystallization temperature of the polymers. The latter were exploited to determine the temperature dependence of the polymer crystallization rate. The results showed the strong influence of the degree of tacticity on the crystallization behaviour of sPP. In particular, it was confirmed that a decrease in the stereo-regularity of the polymer chain considerably shifts the crystallization process to lower temperatures. For the case of the lowest tacticity sample, rheology was crucial in determining the temperature where the maximum (but very small) crystallization rate is attained, a result that could not be achieved by standard calorimetry measurements
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Linear wormlike micelles behave similarly to entangled linear polymers in fast shear flows
No full textWe report shear startup data on solutions of entangled linear wormlike micelles, only differing in the concentration of a binding aromatic salt. Wormlike micelles behave similarly to ordinary polymers in fast shear flows, exhibiting pronounced overshoots as well as tiny undershoots in transient shear viscosity, before approaching the steady state. The analogy is here emphasized by successfully comparing data with predictions of a constitutive equation recently adopted for ordinary entangled polymers. In the fast shear flow, entangled linear wormlike micelles appear to align, stretch, and tumble just like polymeric chains
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