21 research outputs found
Swinging Atwood's Machine: Experimental and Theoretical Studies
A Swinging Atwood Machine (SAM) is built and some experimental results
concerning its dynamic behaviour are presented. Experiments clearly show that
pulleys play a role in the motion of the pendulum, since they can rotate and
have non-negligible radii and masses. Equations of motion must therefore take
into account the inertial momentum of the pulleys, as well as the winding of
the rope around them. Their influence is compared to previous studies. A
preliminary discussion of the role of dissipation is included. The theoretical
behaviour of the system with pulleys is illustrated numerically, and the
relevance of different parameters is highlighted. Finally, the integrability of
the dynamic system is studied, the main result being that the Machine with
pulleys is non-integrable. The status of the results on integrability of the
pulley-less Machine is also recalled.Comment: 37 page
Ignition conditions for inertial confinement fusion targets with a nuclear spin-polarized DT fuel
The nuclear fusion cross-section is modified when the spins of the interacting nuclei are polarized. In the case of deuterium?tritium it has been theoretically predicted that the nuclear fusion cross-section could be increased by a factor d = 1.5 if all the nuclei were polarized. In inertial confinement fusion this would result in a modification of the required ignition conditions. Using numerical simulations it is found that the required hot-spot temperature and areal density can both be reduced by about 15% for a fully polarized nuclear fuel. Moreover, numerical simulations of a directly driven capsule show that the required laser power and energy to achieve a high gain scale as d-0.6 and d-0.4 respectively, while the maximum achievable energy gain scales as d0.9
Low-temperature SCR of NO with NH 3 over noble metal promoted Fe-ZSM-5 catalysts
We have reported previously the excellent performance of Fe-exchanged ZSM-5 for selective catalytic reduction (SCR) of NO with ammonia at high temperatures (300â400 °C). In this work, we found that the reaction temperature could be decreased to 200â300 °C when a small amount of noble metal (Pt, Rh, or Pd) was added to the Fe-ZSM-5. The SCR activity follows the order Pt/Fe-ZSM-5 > Rh/Fe-ZSM-5 > Pd/Fe-ZSM-5 at 250 °C. On the Pt promoted Fe-ZSM-5, 90% NO conversion was obtained at 250 °C at GHSV  = 1.1 Ă 10 5  h â1 . Moreover, the noble metal improved the resistance to H 2 O and SO 2 . The presence of H 2 O and SO 2 decreased the SCR performance only very slightly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44250/1/10562_2004_Article_3462.pd
Singularités irréguliÚre: correspondance et documents
info:eu-repo/semantics/publishedSMF 200