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Joanna M. Goard Philip Broadbridge Daniel J. Arrigo 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1996,47(6):926-942
The nonlinear diffusion equationu
t=[f(u)g(u
x
)] arises in recent models of turbulent transport and of stress dissipation in rock blasting. A Lie point symmetry analysis produces many similarity reductions of exponential and power-law forms, and reveals that for all choices off the equation is always integrable wheng(u
x
)=1/u
x
. We identify the functionsf(u) which guarantee equivalence to the linear heat equation. For all other choices off, the linear canonical form leads to a self-adjoint differential equation by separation of variablesx andt. We construct a number of explicit solutions with simple boundary conditions, which illustrate behavior in the vicinity of the degenerate region withu
x
=. If zero flux and constant concentration are maintained on free boundaries, then steep concentration gradients may evolve from smooth initial conditions. For other boundary conditions, unlike the examples of strong degeneracy, smoothing will occur at initial step discontinuities. 相似文献
997.
998.
999.
T. Case K. M. Crowe K. Lou C. Petitjean W. H. Breunlich M. Jeitler P. Kammel B. Lauss J. Marton W. Prymas J. Zmeskal D. V. Balin V. N. Baturin Yu. S. Grigoriev A. I. Ilyin E. M. Maev G. E. Petrov G. G. Semenchuk Yu. V. Smirenin A. A. Vorobyov N. I. Voropaev P. Baumann H. Daniel F. J. Hartmann M. Mühlbauer W. Schott P. Wojciechowski 《Hyperfine Interactions》1993,82(1-4):295-302
Starting in 1989 an experiment was run at PSI to directly measure the final sticking probability in muon catalyzed dt fusion. This experiment was based on an active-target ionization chamber (IC) built at Gatchina, Russia, and an array of plastic neutron counters. In three runs approximately 5×106 isolated alpha signals were recorded with around one half of these occurring in the inner chamber region where we have more complete understanding of the systematic errors. Particularly from a long run in 1992 we were able to obtain a very clean sticking peak of some 5000 events. However, to reach an accurate value of sticking, all systematic effects and several major backgrounds had to be understood in detail. To this end a Monte Carlo code was written to simulate the full electrostatic environment of the IC and to recreate completely each signal type including the actual tritium decay noise from the live experiment. A slightly model dependent value of approx. 0.56±0.04% is obtained for final sticking. 相似文献
1000.
W. Schott V. N. Baturin W. H. Breunlich T. Case H. Daniel F. J. Hartmann M. Jeitler P. Kammel K. Lou E. M. Maev J. Marton M. Mühlbauer C. Petitjean G. E. Petrov Yu. V. Petrov G. G. Semenchuk Yu. V. Smirenin A. A. Vorobyov P. Wojciechowski J. Zmeskal 《Hyperfine Interactions》1993,82(1-4):471-481
The triton energy of the muon capture reaction 3He t+v, where 3 He is the ground state of muonic3He, has been measured in order to investigate a possible heavy v admixture into the flavour with high sensitivity. 3 He has been formed via the pd fusion reaction by stopping – in an ionization chamber (IC) filled with an H/D gas mixture of 3% D concentration at a pressure of 161 bar. In a first short experiment 650 triton events were observed yielding an upper limit for the -heavy v mixing strength of 2.3×10–3 atE
0v=60 MeV. 相似文献