330,067 research outputs found
Finite-Larmor-radius equilibrium and currents of the Earth’s flank magnetopause
No full textWe consider the one-dimensional equilibrium problem of a shear-flow boundary layer within an ‘extended-fluid model’ of a plasma that includes the Hall and the electron pressure terms in Ohm’s law, as well as dynamic equations for anisotropic pressure for each species and first-order finite-Larmor-radius (FLR) corrections to the ion dynamics. We provide a generalized version of the analytic expressions for the equilibrium configuration given in Cerri et al., (Phys. Plasmas, vol. 20 (11), 2013, 112112), highlighting their intrinsic asymmetry due to the relative orientation of the magnetic field B, b = B/|B| , and the fluid vorticity w = curl(u) (‘ wb asymmetry’). Finally, we show that FLR effects can modify the Chapman–Ferraro current layer at the flank magnetopause in a way that is consistent with the observed structure reported by Haaland et al., (J. Geophys. Res. (Space Phys.), vol. 119, 2014, pp. 9019–9037). In particular, we are able to qualitatively reproduce the following key features: (i) the dusk–dawn asymmetry of the current layer, (ii) a double-peak feature in the current profiles and (iii) adjacent current sheets having thicknesses of several ion Larmor radii and with different current directions
Tesi di Platone sulla ragion politica del processo a Socrate e sulla natura della sua attività propagandistica ’, in AA.VV., Il quinto secolo, Studi di filosofia antica in onore di Livio Rossetti, a cura di S. Giomb‘Tesi di Platone sulla ragion politica del processo a Socrate e sulla natura della sua attività propagandistica Passignano 2010, pp. 519-528
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Towards a Reference Procedure for Designing and Modelling a PSS in the Automotive Industry
No full textAbstractNowadays, PSS lifecycle models are a crucial issue. The management of both the product and the service lifecycle together is recent: to date, there is no evidence of an accepted and operational combined lifecycle model. Furthermore, PSS lifecycle models are based on top-down approach, which are not always suitable from an engineering point of view. The aim of this paper is to propose a reference procedure, built on a bottom-up methodology, for the designing and modeling of PSSs and its lifecycles, applied to the automotive sector
Hot tensile behaviour and cavitation analysis in as-cast and solutionized Al-5.5Mg-Zn alloys
No full textHot tensile test have been performed on Al-Zn-Mg alloy at 250-400°C and 10-3-10-5 s-1 . At the lowest test temperature the stress-strain curves shows a gradual softening after peak while at the other temperatures a plateau is obtained. The microstructural analysis of the polished longitudinal surface of all deformed samples shows that the alloy exhibits cavitation. The cavities have been detected mainly at grain boundaries and particles inclusions. The phenomena limits the hot workability of materials and can cause premature fracture. This paper studies both the relationship between flow curve behaviour and microstructural evolutions and between cavitation, microstructure and process parameters. The main conclusions are the following: 1) Precipitated Zn-Mg particles not are active in crack nucleation, in fact at 250°C cavitation remains almost constant as strain rate decreases. The role of nucleation point of the cavity seems to be related to the constituent particles and segregation as shown by strong reduction of cavitation in the sample solutionized at 490°C-2h before tensile deformation at 250 and 400°C 2) In the investigated range of experimental conditions, the cavity growth is mainly driven by plastic straining and the fracture type is transgranular ductil
Neural management for heat and power cogeneration plants
No full textThis paper deals with the problem of finding the optimum load allocation on machines and apparatuses in complex Cogeneration Heat and Power (CHP) plants. A methodology based on Neural Networks (NN) has been developed. A database has been populated by using a real plant simulator.
Two kinds of plant neural models have been trained, the first consists in an Identification Neural Model (INM) that provides a ‘‘picture’’ of the actual plant status by using monitoring data as input; the second consists in an Optimum Load Allocation Neural Model (OLANM) whose inputs are boundary conditions and outputs the Degrees of Freedom corresponding to the optimum operation set points. To reduce the relevant computational effort required to populate the training databases a sequential chain of neural models has been arranged. The method has been applied to a real cogeneration plant. The developed Plant Optimization Neural Tool (PONT) has shown a good capability to modify load allocation when the status of components and boundary conditions vary.
The computational time required is really small (some 500 ms). The accuracy in achieving the solution is comparable with that of traditional physical-empirical plant simulators.
These achievements show the potentialities of the neural approach for real time or quasi-real time applications to support plant management decisions
Knowledge Communication: motivation and foundations
No full textWe reflects about the difference between knowledge systems and knowledge communi cation systems. Most real world situations are inherently open: there is a need for unforeseen interactions with external autonomous agents such as humans or programs. In addition, the trends in softwar e show evidences for modularization and collaboration among "objects" exchanging messages. For these reasons, the theme of understanding the partner in dialogues becomes central. In order to do that, we have to build models and tools for experimenting with dialogues. In the position paper : a. we outline the motivation for distinguishing between knowledge systems and kn owledge communication systems ; b.we present a brief review of the author's research lines attempting at solutions for the consequences of the difference. 1 Introduction In previous papers [Cerri 86; Cerri and McIntyre 91] it was argued that human-comp uter communication in tutoring systems and information systems requires a sub..
Man nehme 14 Tage, 13 Dozentinnen, 8 europäische Universitäten, 47 Studierende
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