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111.
Robert McLachlan 《Numerische Mathematik》1993,66(1):465-492
Summary The numerical integration of a wide class of Hamiltonian partial differential equations by standard symplectic schemes is discussed, with a consistent, Hamiltonian approach. We discretize the Hamiltonian and the Poisson structure separately, then form the the resulting ODE's. The stability, accuracy, and dispersion of different explicit splitting methods are analyzed, and we give the circumstances under which the best results can be obtained; in particular, when the Hamiltonian can be split into linear and nonlinear terms. Many different treatments and examples are compared. 相似文献
112.
113.
Dieter Lutz 《Aequationes Mathematicae》1981,23(1):197-203
In this note it is shown that the Cauchy problem associated with the infinitesimal generatorA of a strongly continuous operator cosine function remains uniformly well-posed under bounded time-dependent perturbations ofA. 相似文献
114.
The analogues of the low-lying levels in71Ge have been observed as resonances in the compound nucleus71As through proton elastic scattering on70Ge in the energy rangeE
p=3.5 to 5.3 MeV. The excitation functions cover the analogue resonances corresponding to states upto 2.3 MeV excitation in71Ge. The sub-structures in the 5.06 MeV resonance, first observed by Temmer and co-workers have been confirmed in the present
experiment. The present investigation reveals similar sub-structures in the 4.13 MeV resonance lending further support to
the existence of intermediate structure near an isobaric analogue resonance. The resonance parameters and the spectroscopic
factors (for the corresponding parent states) have been extracted. The results are compared with the information available
from the70Ge(d, p)71Ge reaction. 相似文献
115.
116.
The forms of the exceptional simple classical Lie
superalgebras are determined over arbitrary fields of
characteristic $\ne 2,3$. 相似文献
117.
Hong-Ming Yin 《Journal of Differential Equations》2004,200(1):137-161
In this paper we first study the regularity of weak solution for time-harmonic Maxwell's equations in a bounded anisotropic medium Ω. It is shown that the weak solution to the linear degenerate system, , is Hölder continuous under the minimum regularity assumptions on the complex coefficients γ(x) and ξ(x). We then study a coupled system modeling a microwave heating process. The dynamic interaction between electric and temperature fields is governed by Maxwell's equations coupled with an equation of heat conduction. The electric permittivity, electric conductivity and magnetic permeability are assumed to be dependent of temperature. It is shown that under certain conditions the coupled system has a weak solution. Moreover, regularity of weak solution is studied. Finally, existence of a global classical solution is established for a special case where the electric wave is assumed to be propagating in one direction. 相似文献
118.
Let v be a valuation of terms of type , assigning to each term
t of type a value v(t) 0. Let
k 1 be a natural number. An identity
of type is called
k-normal
if either s = t or both
s and t have value
k, and otherwise is called non-k-normal. A
variety V of type is said to be k-normal if
all its identities are k-normal, and non-k-normal
otherwise. In the latter case, there is a unique smallest k-normal variety
to contain V , called the k-normalization of
V. Inthe case k = 1, for the usual depth valuation
of terms, these notions coincide with the well-known concepts of normal identity, normal variety, and
normalization of a variety. I. Chajda has characterized the normalization of a variety by means of choice algebras. In
this paper we generalize his results to a characterization of the k-normalization of
a variety, using k-choice algebras. We also introduce the concept of a
k-inflation algebra, and for the case that v is the
usual depth valuation of terms, we prove that a variety V is
k-normal iff it is closed under the formation of k-inflations,
and that the k-normalization of V consists
precisely of all homomorphic images of k-inflations of algebras in V . 相似文献
119.
We study the structure of rings that are sums of two subrings one of which is nil and the other reduced. Our main results concern the problem whether in this situation the nil subring must be an ideal.Received: 13 July 2001 相似文献
120.
Let n be a positive integer and P=diag(−In−κ,Iκ,−In−κ,Iκ) for some integer κ∈[0,n]. In this paper, we prove that for any convex compact smooth hypersurface Σ in R2n with n?2 there always exists at least one closed characteristic on Σ which possesses at least 2n−4κ Floquet multipliers on the unit circle of the complex plane, provided Σ is P-symmetric, i.e., x∈Σ implies Px∈Σ. 相似文献