Search results for "confine"
showing 10 items of 285 documents
Relativistic constituent quark model with infrared confinement
2009
We refine the relativistic constituent quark model developed in our previous papers to include the confinement of quarks. It is done, first, by introducing the scale integration in the space of alpha-parameters, and, second, by cutting this scale integration on the upper limit which corresponds to an infrared cutoff. In this manner one removes all possible thresholds presented in the initial quark diagram. The cutoff parameter is taken to be the same for all physical processes. We adjust other model parameters by fitting the calculated quantities of the basic physical processes to available experimental data. As an application, we calculate the electromagnetic form factors of the pion and t…
Confined quarks and the neutrinoless ββ decay
1990
Abstract The half life of the neutrinoless double beta decay of 76Ge into the ground state of 76Se is calculated in a relativistic quark confinement model. The neutron-proton quasi-particle random phase approximation is used to evaluate the nuclear matrix elements involved in the decay amplitude. We avoid the closure approximation, but compare our results with this approximation. From the experimental half life we deduce an upper limit for the Majorana mass of the neutrino and estimate the right-handed contribution to the charged weak current.
Propan-2-ol dehydration on H-ZSM-5 and H-Y zeolite: a DFT study
2012
The catalytic dehydration of propan-2-ol over H-Y and H-ZMS-5 aluminated zeolite models, mimicking both internal cavities and external surfaces, was studied by DFT calculations to investigate the reaction mechanism. After the adsorption of propan-2-ol on the zeolite, the dehydration mechanism starts with alcohol protonation, occurring by one acidic –OH group of the zeolite fragment, followed by a concerted β-elimination to give propene. The catalytic activity is affected by the size of the zeolite cavity, which is larger in the H-Y than in the H-ZMS-5 zeolite. The adsorption energy of the reagent, as an example, decreases in the order: H-Y cavity ≃ H-ZMS-5 surface > H-ZMS-5 cavity, pointing…
Stress-strain models for normal and high strength confined concrete: Test and comparison of literature models reliability in reproducing experimental…
2017
SUMMARY: The adoption of proper constitutive laws for confined concrete is basic for seismic assessment of new and existing reinforced concrete civil structures. The deformation capacity of reinforced concrete (RC) columns subjected to axially centred and eccentric loads depends on the effectiveness confinement action. A proper assignment of the stressstrainlaws for concrete allows obtaining an adequate definition of the ductility of the crosssections and correctly identifying mechanical nonlinearities in computational models.Several studies concerning the behaviour of confined concrete have been carried out, highlighting the role of different geometrical and mechanical parameters to the ov…
Pratiques d'enseignement - apprentissage en contexte de confinement : « continuité » ou rupture pédagogique ? La recherche action EDiCOViD
2021
International audience
Structure and Dynamics of Confined Liquids: Challenges and Perspectives for the X-ray Surface Forces Apparatus
2019
Preprint of the open access article Weiss, H., Cheng, H.-W., Mars, J., Li, H., Merola, C., Renner, F. U., Honkimäki, V., Valtiner, M., & Mezger, M. (2019). Structure and Dynamics of Confined Liquids: Challenges and Perspectives for the X-ray Surface Forces Apparatus. Langmuir, 35(51), 16679–16692. https://doi.org/10.1021/acs.langmuir.9b01215
Direct interpretation of near-field optical images
2001
International audience; The interpretation of the detection process in near-field optical microscopy is reviewed on the basis of a discussion about the possibility of establishing direct comparisons between experimental images and the solutions of Maxwell equations or the electromagnetic local density of states. On the basis of simple physical arguments, it is expected that the solutions of Maxwell equations should agree with images obtained by collecting mode near-field microscopes, while the electromagnetic local density of states should be considered to provide a practical interpretation of illumination mode near-field microscopes. We review collecting mode near-field microscope images w…
Analysis of metallic impurity content by means of VUV and SXR diagnostics in hybrid discharges with hot-spots on the JET-ITER-like wall poloidal limi…
2019
In preparation for the upcoming JET D-T campaign, great effort has been devoted during the 2015-2016 JET campaigns with the ITER-like wall (ILW) to the extension of the high performance H-mode phase in baseline and hybrid scenarios. Hybrid discharges were the only ones that have been stopped by the real-time vessel protection system due hot-spot formation on the outboard poloidal limiter. Generation of hot-spots was linked to the application of high neutral beams injection and ion cyclotron resonance heating (ICRH) power. In tokamaks with high-Z plasma components, the use of ICRH heating is also accompanied by an increased metallic impurity content. Simultaneous control of hot-spot temperat…
Covid-19 : quel bilan critique ? (Partie II)
2021
International audience
Covid-19 : quel bilan critique ? (Partie I)
2021
International audience