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81.
研究了有15个部件串并联工作的多状态口香糖生产可修复系统.运用C_0半群的理论,证明了系统算子是稠定的预解正算子,得出了系统算子的共轭算子及其定义域,并证明了系统算子的增长界为0.最后运用了预解正算子中共尾的概念及相关理论,证明了系统算子的谱上界也是0. 相似文献
82.
83.
We investigate two different discretization approaches of a model optimal-control problem, chosen to be relevant for control
of instabilities in shear flows. In the first method, a fully discrete approach has been used, together with a finite-element
spatial discretization, to obtain the objective function gradient in terms of a discretely-derived adjoint equation. In the
second method, Chebyshev collocation is used for spatial discretization, and the gradient is approximated by discretizing
the continuously-derived adjoint equation. The discrete approach always results in a faster convergence of the conjugate-gradient
optimization algorithm. Due to the shear in the convective velocity, a low diffusivity in the problem complicates the structure
of the computed optimal control, resulting in particularly noticeable differences in convergence rate between the methods.
When the diffusivity is higher, the control becomes less complicated, and the difference in convergence rate reduces. The
use of approximate gradients results in a higher sensitivity to the degrees of freedom in time. When the system contains a
strong instability, it only takes a few iteration to obtain an effective control for both methods,even if there are differences
in the formal convergence rate. This indicates that it is possible to use the approximative gradients of the objective function
in cases where the control problem mainly consists of controlling strong instabilities.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
84.
Maxim Kontsevich 《Compositio Mathematica》1999,115(1):115-127
We show that recently constructed invariants of 3-dimensional manifolds and of hyperkähler manifolds (L. Rozansky and E. witten) come from characteristic classes of foliations and from Gelfand-fuks cohomology. 相似文献
85.
In this work it is proved that the geometry of the well-known quantization scheme of general gauge theories, the so-called
Batalin–Vilkovisky formalism, is the odd Riemannian geometry.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 28–31, November, 2008. 相似文献
86.
87.
The scattering theory for the Klein Gordon equation, with time-dependent potential and in a non-static space-time, is considered.
Using the Klein Gordon equation formulated in the Hubert spaceL
2(R
3) and the Einstein’s relativistic equation in the spaceL
2(R
3, dx) and establishing the equivalence of the vacuum states of their linearized forms in the Hubert spaceL
2(R
3) with the help of unique symmetric symplectic operator, the time evolution unitary operatorU(t) has been fixed for the Klein Gordon equation, incorporating either the positive or negative frequencies, in the infinite
dimensional Hubert spaceL
2(R
3). 相似文献
88.
In this paper,the modern geometrical structure of analytical mechanics,the exteriordifferential forms and the geometrical meaning of dynamic equations are briefly discussed. 相似文献
89.
90.
V. I. Agoshkov E. A. Botvinovskii 《Computational Mathematics and Mathematical Physics》2007,47(7):1142-1157
Methods in optimal control and the adjoint-equation theory are applied to the design of iterative algorithms for the numerical solution of the nonstationary Stokes system perturbed by a skew-symmetric operator. A general scheme is presented for constructing algorithms of this kind as applied to a broad class of problems. The scheme is applied to the nonstationary Stokes equations, and the convergence rate of the corresponding iterative algorithm is examined. Some numerical results are given. 相似文献