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781.
Yoshikazu Giga Kazuyuki Yama-uchi 《Calculus of Variations and Partial Differential Equations》1993,1(4):417-428
This paper considers a generalized evolution of a compact closed (hyper)-surface moved by its mean curvature. By a comparison of a shrinking ball the surface extincts in a finite time. An estimate of the extinction time from above is given by L. C. Evans and J. Spruck. In this paper we give an estimate from blow. In fact we proved that the extinction time is estimated from below by to times the square of the volume of a set enclosed by the initial surface over the initial area of the surface. The constant two is optimal.Partly supported by the Inamori Foundation 相似文献
782.
It is shown that a special case of the well-known Lojasiewicz gradient inequality is sufficient to give a unified background
for many convergence results in gradient or gradient-like systems appearing previously in the Literature. Besides as an illustration
we give a direct proof of convergence in the case of 1D wave equations by a suitable adaptation of Zelenyak’s method. 相似文献
783.
Thomas Hermann 《Numerical Algorithms》1996,13(2):307-320
The stability of transformations between Taylor and Hermite and Bernstein and Hermite forms of the polynomials are investigated. The results are analogous to Farouki's concerning the stability of the transformation between Taylor and Bernstein form. An exact asymptotic is given for the condition numbers in thel
1 case.Research was partially supported by the Copernicus grant RECCAD 94-1068 and by the National Research Foundation of the Hungarian Academy of Sciences grant 16420. 相似文献
784.
M. Götz 《Monatshefte für Mathematik》2002,136(2):99-121
This paper is devoted to an estimation of the error of integration with respect to arbitrary unit measures μ and ν on only in terms of continuity or smoothness properties of the function f and the discrepancy . Here, stands for certain classes of (Borel-) test sets. The proofs are in part based on a continuous wavelet analysis of the integrated
function by means of Haar-type wavelets.
Received 26 January 2001; in revised form 23 September 2001 相似文献
785.
José G. Llavona 《Mediterranean Journal of Mathematics》2006,3(2):259-271
This paper is a survey of approximation results and methods by smooth functions in Banach spaces. The topics considered in
the paper are the following: approximation by polynomials by Ck-functions using the method of smooth partitions of unity, approximation by the fine topology, analytic approximation and
regularization in Banach spaces using the infimal convolution method. 相似文献
786.
Manuel De la Sen 《Positivity》2007,11(2):319-340
This paper discusses non-negativity and positivity concepts and related properties for the state and output trajectory solutions
of dynamic linear time-invariant systems described by functional differential equations subject to point time-delays. The
various non-negativity and positivity introduced hierarchically from the weakest one to the strongest one while separating
the corresponding properties when applied to the state space or to the output space as well as for the zero-initial state
or zero-input responses. The formulation is developed by defining cones for the input, state and output spaces of the dynamic
system. 相似文献
787.
U. Luther 《Annali di Matematica Pura ed Applicata》2003,182(2):161-200
We show that the representation theorem for classical approximation spaces can be generalized to spaces A(X,l
q
(ℬ))={f∈X:{E
n
(f)}∈l
q
(ℬ)} in which the weighted l
q
-space l
q
(ℬ) can be (more or less) arbitrary. We use this theorem to show that generalized approximation spaces can be viewed as real
interpolation spaces (defined with K-functionals or main-part K-functionals) between couples of quasi-normed spaces which satisfy certain Jackson and Bernstein-type inequalities. Especially,
interpolation between an approximation space and the underlying quasi-normed space leads again to an approximation space.
Together with a general reiteration theorem, which we also prove in the present paper, we obtain formulas for interpolation
of two generalized approximation spaces.
Received: December 6, 2001; in final form: April 2, 2002?Published online: March 14, 2003 相似文献
788.
50nm SOI-DTMOS器件的性能 总被引:1,自引:0,他引:1
利用二维器件模拟软件ISE对5 0nm沟道长度下SOI DTMOS器件性能进行了研究,并与常规结构的SOI器件作了比较.结果表明,在5 0nm沟长下,SOI DTMOS器件性能远远优于常规SOI器件.SOI DTMOS器件具有更好的亚阈值特性,其亚阈值泄漏电流比常规SOI器件小2~3个数量级,从而使其具有更低的静态功耗.同时,SOI DTMOS器件较高的驱动电流保证了管子的工作速度,并且较常规SOI器件能更有效地抑制短沟道器件的穿通效应、DIBL及SCE效应,从而保证了在尺寸进一步减小的情况下管子的性能.对SOI DTMOS器件的物理机制进行了初步分析,揭示了其性能远优于常规结构的物理本质 相似文献
789.
Summary. In this paper we derive an error bound for the large time step, i.e. large Courant number, version of the Glimm scheme when used for the approximation
of solutions to a genuinely nonlinear, i.e. convex, scalar conservation law for a generic class of piecewise constant data.
We show that the error is bounded by for Courant numbers up to 1. The order of the error is the same as that given by Hoff and Smoller [5] in 1985 for the Glimm
scheme under the restriction of Courant numbers up to 1/2.
Received April 10, 2000 / Revised version received January 16, 2001 / Published online September 19, 2001 相似文献
790.
This paper studies systems of tensor-product functions for which the functions they span are monotonic in any direction when
their control nets are monotonic in that direction. It is shown that Bernstein polynomials and B-splines have this property
but that totally positive systems in general, such as certain trigonometric and rational bases, do not.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献