Results 1 - 10 of 1080
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[en] An extensive review on extrusion processes is presented. The various applications, parameters and their influence on the process and on the quality of the products, were scanned. Special attention is given to the two main processes, conventional extrusion and hydrostatic extrusion. (author)
[en] Nuclear astrophysics aims to measure nuclear-reaction cross sections of astrophysical interest to be included into models to study stellar evolution and nucleosynthesis. Low energies, < 100 keV, are requested for this is the window where these processes are more effective. Two effects have prevented to achieve a satisfactory knowledge of the relevant nuclear processes, namely the Coulomb barrier exponentially suppressing the cross section and the presence of atomic electrons. These difficulties have triggered theoretical and experimental investigations to extend our knowledge down to astrophysical energies. For instance, indirect techniques such as the Trojan Horse Method and new experimental facilities such as deep underground laboratories have been devised yielding new cutting-edge results.
[en] In this work the elastic behaviour of metal powders compacted to different densities is studied. The authors apply a model based on the experimental observation that the elastic volumetric strain and the hydrostatic component of the applied stress are exponentially related. While a complete analysis should include both the volumetric and deviatoric components of the elastic strain, we only present here the first one. (Author) 9 refs
[en] The invention concerns self lubricating fluid bearings, which are used in a shaft sealed system extending two regions. These regions contain fluids, which have to be isolated. A first seal is fluid tight for the first region between the carter shaft and the shaft. The second seal is fluid tight between the carter and the shaft, it communicates with the second region. The first fluid region is the environment surrounding the shaft carter. The second fluid region is a part of a nuclear reactor which contains the cooling fluid. The shaft is conceived to drive a reactor circulating and cooling fluid
[fr]L'invention concerne des paliers autolubrifiants a fluide que l'on utilise dans un systeme de joint d'un arbre s'etendant entre deux regions contenant des fluides qu'il s'agit d'isoler l'un de l'autre. Un premier joint est dispose en relation d'etancheite entre le carter de l'arbre et l'arbre lui-meme aupres de la premiere region de fluide et un deuxieme joint est adapte de facon etanche entre le carter et l'arbre et communique avec la deuxieme region de fluide. La premiere region de fluide est l'environnement entourant le carter d'arbre et la deuxieme region de fluide est une partie d'un reacteur nucleaire qui contient du fluide de refroidissement. L'arbre est concu pour entrainer un circulateur de fluide de refroidissement du reacteur
[en] Highlights: • Diamagnetic susceptibility (DMS) of doped quantum dot is studied. • Hydrostatic pressure (HP) and temperature (T) affect DMS. • The dot is subjected to Gaussian white noise. • DMS also depends on mode of application of noise. - Abstract: We explore the diamagnetic susceptibility (DMS) of impurity doped quantum dot (QD) in presence of Gaussian white noise and under the combined influence of hydrostatic pressure (HP) and temperature (T). Presence of noise and also its mode of application discernibly affect the DMS profile. Application of HP and T invites greater delicacies in the observed DMS profiles. However, whereas the interplay between T and noise comes out to be extremely sensitive in fabricating the DMS profile, the pressure-noise interplay appears to be not that much noticeable. Under all conditions of temperature and pressure, the presence of multiplicative noise diminishes the value of DMS in comparison with that in presence of its additive analogue. The present study renders a deep insight into the remarkable role played by the interplay between noise, hydrostatic pressure and temperature in controlling the effective confinement imposed on the system which bears unquestionable relevance.
[en] The classical way to treat incompressible linear elastic materials is to use the inverse constitutive relationship (strain as a function of the stress), based on the compliance tensor, in place of the direct constitutive equation (stress as a function of strain), based on the elasticity (stiffness) tensor. This is because the elasticity tensor is affected by a diverging bulk modulus, requiring in order to allow the material to sustain any hydrostatic load, and is therefore not defined. In this work we show that there is a part of the elasticity tensor that can be saved also for incompressible materials, by filtering the components that deal with hydrostatic loads. The procedure is based on the treatment of incompressibility by means of the constant of isochoric motion, i.e. of conservation of volume, and fourth-order tensor algebra.
[en] Electrical measurements under increasing hydrostatic pressure (1-4000 [bar]) have shown that electrical conductivity is closely related to the iodine doping rate (0-14%) of polyacetylene (PA) films. In pristine PA, conductivity increases with pressure while in 14% iodinedoped PA it decreases. A most important result is noticed for an intermediate doping rate (1.5%). In fact, for sweeping of the range of pressure, conductivity decreases in the beginning and then increases with pressure augmentation. This change is located at a critical pressure Pc. An empirical formula was proposed to describe this behaviour. The aim of this work is to contribute to the greater understanding of the pressure effect on the transport mechanism and/or the nature of charge carriers. (author)