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91.
We show that, when numerically integrating Hamiltonian problems, nondissipative numerical methods do not in general share the advantages possessed by symplectic integrators. Here a numerical method is called nondissipative if, when applied with a small stepsize to the test equationdy/dt = iy, real, has amplification factors of unit modulus. We construct a fourth order, nondissipative, explicit Runge-Kutta-Nyström procedure with small error constants. Numerical experiments show that this scheme does not perform efficiently in the numerical integration of Hamiltonian problems.This research has been supported by project DGICYT PB92-254. 相似文献
92.
Krzysztof Ciesielski 《Periodica Mathematica Hungarica》1995,31(1):11-20
In the paper we prove that the complex analytic functions are (ordinarily) density continuous. This stays in contrast with the fact that even such a simple function asG:22,G(x,y)=(x,y
3
), is not density continuous [1]. We will also characterize those analytic functions which are strongly density continuous at the given pointa . From this we conclude that a complex analytic functionf is strongly density continuous if and only iff(z)=a+bz, wherea, b andb is either real or imaginary. 相似文献
93.
We obtain the complete set of states of theq-oscillator in both configuration space and momentum space as well as the transformation between these spaces. The states as well as the matrix elements lie in the SU
q
(2) algebra. To obtain transition probabilities, one must take the Woronowicz square. 相似文献
94.
M. Weiden J. Köhler G. Sparn M. Köppen M. Lang C. Geibel F. Steglich 《Zeitschrift für Physik B Condensed Matter》1995,98(2):167-169
We present an investigation of the spin-Peierls transition atT
SP=14.5 K in polycrystalline CuGeO3 through specific-heat and thermal-expansion measurements. Clear second-order phase-transition anomalies are found in both properties atT
SP, although only a small entropy of S0.1 Rn2 is released at the transition. Most of the entropy is released atT
SP<T<150 K, where the temperature dependence of the magnetic contribution to the specific heat as well as the thermal expansion exhibit extrema atT
*40 K. These are caused by one-dimensional antiferromagnetic fluctuations along the Cu chains, possibly accompanied by structural fluctuations. Using Ehrenfest's relation, a hydrostatic pressure coefficient (T
SP/p)p0 (0.45±0.06) K/kbar is derived. 相似文献
95.
The main objective of this paper is to solve the functional equation
相似文献
96.
IfA is a -algebra on setX, thenl
0
(X,A) is a barrelled space of class 0. IfA is an algebra, there are conditions which imply thatl
0
(X,A) is suprabarelled. Here, wheneverA is an algebra, we give conditions forl
0
(X,A) to be not barrelled which are related with the existence of non-trivial convergent sequences.Supported in part by DGICYT, project PB91-0407 and by the Institució Valenciana d'Estudis i Investigació, project 023. 相似文献
97.
Maria Rosaria Enea 《Geometriae Dedicata》1994,51(3):257-286
In this paper we develop a structure theory of algebraic right distributive quasigroups which correspond to closed and connected conjugacy classes
generating algebraic Fischer groups (in the sense of [6]) such that the mappingx x
–1
ax, fora
, is an automorphism of
(as variety). We also give examples of algebraic Fischer groups where this does not happen. It becomes clear that the class of algebraic right distributive quasigroups has nice properties concerning subquasigroups, normal subquasigroups and direct product.We give a complete classification of one- and two-dimensional as well as of minimal algebraic right distributive quasigroups. 相似文献
98.
In this paper we consider a class of systems described by singular integrodifferential equations. This type of systems appear, for example, in the modeling of certain aeroelastic control problems. We study these systems in frequency domain framework and show the existence of finite-dimensional stabilizing controllers. An algorithmic procedure is outlined for the construction of such controllers. In order to illustrate the numerical aspects of this algorithm, we present an example involving the classical Theodorsen model of an airfoil, which fits in the class of systems considered here.This work was supported in part by the National Science Foundation under Grants DMS-8907019 and MSS-9203418. 相似文献
99.
Hermann Thorisson 《Probability Theory and Related Fields》1994,99(4):477-483
Summary The result linking shift-coupling to time-average total variation convergence and to the invariant -field is extended to continuous time and an analogous result established linking -couplings to smooth total variation convergence and to a smooth tail -field. Shift- and -coupling inequalities are presented. 相似文献
100.
M. B. Freiler M. C. Shih S. Kim M. Levy I. P. Herman R. Scarmozzino R. M. Osgood Jr. 《Applied Physics A: Materials Science & Processing》1996,63(2):143-151
We present a study of pattern-transfer and etch-induced damage in photon-induced cryoetching. Features with effective radii as small as 100 nm have been formed in both bulk and layered GaAs/AlGaAs materials. A measurement of the photoluminescence of etch-defined deep- submicrometer structures material suggests that this form of etching results in minimal process-induced damage. Modeling of the luminescence vs feature size for these features shows that the luminescence is limited only by carrier diffusion and non-radiative surface recombination. 相似文献
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