130,849 research outputs found
Sierre, Boso von an Gr. St. Bernhard (Mont Joux) - 29.8.1244
No full textzu03: 1244 VIII 29 Sitten im Haus des Sakristans Boso v. Sierre; zu07: Affiliés à l'ordre et donationsº D 1244 VIII 29; zu13: Boso v. Sierre (Dom-)Sakristan v. Sitten durch Notar Wilhelm im Auftrag des Kanzlers und (Dom-)Kantors Walter v. Sitten; zu15: Ulrich , Neffe des Boso v. Sierre; Art d. Kopie: 3N + 2Ind. + 4Pos.; zu16: Perg. gebräunt, vor allem im linken und rechten Randbereich, Bleiliniierung, Textblock links begrenzt.{'name': 'DFG', 'uri': 'dfg.png'
Electro-mechanical problems in superconductiong coils
No full textThis paper presents the most recent research activity performed by the authors in the field of contact problems in superconducting coils. The research is related to the development of the coils for the experimental nuclear fusion machine “ITER”. The results here summarized are related to the inter-strand electromechanical behavior and its dependence on the electromechanical contact resistance. The effects related to the distribution of the superconducting zones within the wire, and of the mechanical properties of the materials are presented. Moreover a microscopical formulation for a more accurate treatment of the contact resistance is formulated. The adopted strategy is based on the statistical characterization of the surface roughness and the electro-mechanical behavior of the contacting asperities. In such a way the contact resistance is build up starting from a physical background
A numerical formulation for electric-mechanical contacts based on microscopic interface laws
No full textThis work is devoted to the development of a new constitutive model for electric–mechanical contacts, based on a micro-macro approach to describe the contact behaviour.
In order to model properly the physical aspect of the problem the surface microrugosity must be considered. In the proposed contact element a macroscopic formulation, based on microscopic evidences, is set up and implemented in the contact formulation.
Some thermo-mechanical macroscopic models, based on microscopic characterizations, have already been developed to compute the normal and tangential contact stiffness and the thermal contact resistance. On the basis of such macroscopic models, a similar model, suitable for the electric-mechanical field, is developed. With reference to the thermal constriction resistance the electric contact resistance is studied, assuming a flux tube around each contacting asperity, and choosing a suitable geometry for its narrowing at the contact zone.
Finally these selected microscopic laws are adapted to the macroscopic numerical necessities to obtain a constitutive law for the electric-mechanical contact element.
Consistent linearization is developed in order to improve the computational speed, within the framework of the implicit methods
A formulation for electric-mechanical contact and its numerical solution
No full textThe progress in advanced technology fields requires more and more sophisticated formulations to consider contact problems properly. This paper is devoted to the development of a new constitutive model for electrostatic–mechanical contacts, based on a micro-macro approach to describe the contact behaviour. The electric-mechanical contact constitutive law is obtained considering the real microscopic shape of the contacting surfaces, the microscopic behaviour of force transmission and current flow. Some thermo-mechanical macroscopic models based on microscopic characterizations have already been developed to compute the normal and tangential contact stiffness and the thermal contact resistance. On the basis of such macroscopic models, a similar model, suitable for the electric-mechanical field, is developed. With reference to the thermal constriction resistance the electric contact resistance is studied, assuming a flux tube around each contacting asperity, and choosing a suitable geometry for its narrowing at the contact zone. The contact element geometry is based on well known theoretical and experimental micro-mechanical laws, suitably adapted for the FEM formulation. The macroscopic stiffness matrix is calculated on the basis of the microscopic laws and it is continuously updated as a function of the changes in the mechanical and electric significant parameters. A consistent linearization of the set of equations is developed to improve the computational speed, within the framework of implicit methods
A Combined Electromagnetic and Mechanical Approach for EU-DEMO Toroidal Field Coils
No full textThe roadmap to fusion electricity of the European scientific program aims at the realization of the future DEMOnstration (DEMO) fusion power plant. In 2020, the pre-concept design phase of DEMO was completed, defining the concept and characteristics of the main magnets and structures of the machine. Sixteen toroidal D-shaped magnets, six poloidal annular coils and a central solenoid constitute the functioning system core. The reactor is subjected to huge mechanical loads, mainly due to the Lorentz force produced by the combination of the high magnetic fields and operative currents. As a consequence, the loading conditions are extremely demanding for the structural components, and it is crucial to complete a comprehensive static and fatigue assessment before proceeding with the next design iteration. This work focuses on the electromagnetic and structural analyses performed on the toroidal field coil system and its support structures to present the methodological approach developed. Exploiting the finite element method, a three-dimensional model has been defined to obtain the electromagnetic loads on the main time points of the reference plasma scenario and then transfer them to a related 3D structural model, corresponding to the discretization of the electromagnetic one. The structural model was used to obtain the displacement and stress fields at the various time points to perform the mechanical evaluation as well as the fatigue assessment
Modeling a Multistrand SC Cable with an Electrical DC Lumped Network
No full textThe paper presents a procedure for the numerical computation of the global interstrand resistances measured between strands of superconducting multistrand cables. The procedure is based on a geometrical reconstruction of the cable strands geometries, which are used to generate an electrical equivalent DC lumped network. In this network, the strands are represented by ideal short circuits and the geometrical points of contact between the strands correspond to lumped conductances. The network is completed with a suitable arrangement of connections between strands and DC power supplies. The network equations are then solved numerically and the strand currents are evaluated together with the interstrand voltages. The accuracy of the procedure is discussed through a comparison with experimental results
Background seismicity in Boso Peninsula, Japan: long-term acceleration, and relationship with slow slip events
No full textSlow slip events (SSEs) in subduction zones can trigger earthquake swarms, especially at shallow depth. The monitoring of seismicity rates has therefore the potential to help detect and characterize SSEs, and transient changes in coupling. However, the relationship between seismicity rate and slow slip rate during a SSE is unknown and made complicated by aftershock triggering within the swarm. Here we propose to complement geodetic methods with an objective measure of the seismicity rate that is directly associated with changes in slip rate. We show that this measure, applied to known occurrences of SSEs in the Boso area, Japan, yields an estimate, albeit indirect, of their seismic moment, hence their slip rate. We finally prove that the background rate in Boso has been accelerating since 1990; this explains previous observations of the shortening of the recurrence time between SSEs in Boso, that clearly predate the 2011 Mw9.0 Tohoku-Oki earthquake.T. Reverso, D. Marsan, A. Helmstetter and B. Enesc
A microscopical model for electric-mechanical contact
No full textIn this paper a model to deal with electric-mechanical contact problems in the framework of the FEM is presented. On the basis of some micro-mechanical studies, a new approach is developed to define the non-linear constitutive law that governs the normal force-displacement behaviour and the electric resistance of the contacting surfaces
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