共查询到12条相似文献,搜索用时 15 毫秒
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We prove a local index theorem for families of \(\bar \partial \) -operators on Riemann surfaces of type (g, n), i.e. of genusg withn>0 punctures. We calculate the first Chern form of the determinant line bundle on the Teichmüller spaceT g,n endowed with Quillen's metric (where the role of the determinant of the Laplace operators is played by the values of the Selberg zeta function at integer points). The result differs from the case of compact Riemann surfaces by an additional term, which turns out to be the Kähler form of a new Kähler metric on the moduli space of punctured Riemann surfaces. As a corollary of this result we derive, for instance, an analog of Mumford's isomorphism in the case of the universal curve. 相似文献
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H. M. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(4):563-568
There has been a debate in the transportation research
community over the validity of a class of traffic flow models.
These models have the peculiar property that one of its characteristic speeds
is faster than that of vehicular traffic. This note attempts to
provide an overview of the diverging views on how to interpret this property, and
specific comments on the interpretation of Helbing and Johansson [On the controversy around
Daganzo’s requiem for and Aw-Rascle’s resurrection of second-order
traffic flow models, Eur. Phys. J. B (2009), DOI: 10.1140/epjb/e2009-00182-7].
We showed that having faster-than-traffic characteristics does
produce counterintuitive predictions, and they cannot be explained
away by a linear stability analysis. As such, the existence of such
characteristics must be justified by the physics of traffic, and
verified through empirical observations. 相似文献
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D. Helbing 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(4):569-570
This contribution compares several different approaches allowing one to derive macroscopic traffic equation directly from
microscopic car-following models. While it is shown that some conventional approaches lead to theoretical problems, it is
proposed to use an approach reminding of smoothed particle hydrodynamics to avoid gradient expansions. The derivation circumvents
approximations and, therefore, demonstrates the large range of validity of macroscopic traffic equations, without the need
of averaging over many vehicles. It also gives an expression for the “traffic pressure”, which generalizes previously used
formulas. Furthermore, the method avoids theoretical inconsistencies of macroscopic traffic models, which have been criticized
in the past by Daganzo and others. 相似文献
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It is shown that on a compact spin symmetric space with a Kähler or Quaternion-Kähler structure, the first eigenvalue of the Dirac operator is linked to a “lowest” action of the holonomy, given by the fiberwise action on spinors of the canonical forms characterized by this holonomy. The result is also verified for the symmetric space , proving that it is valid for all the “possible” holonomies in Berger’s list occurring in that context. The proof is based on a characterization of the first eigenvalue of the Dirac operator given in Milhorat (2005) and Milhorat (2006). By the way, we review an incorrect statement in the proof of the first lemma in Milhorat (2005). 相似文献
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《Annals of Physics》1986,166(1):250-252
In a recent paper on the theory of subdynamics, Ch. Obcemea and E. Brändas (Ann. Phys (N.Y.)151 (1983), 383–430) claimed to correct a recently published result (M. Courbage, J. Math. Phys.23 (1982), 646, 652). It is shown that this criticism is unfounded. Some additional remarks are made. 相似文献
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《Surface science》1989,217(3):L435-L440
A recent article [Surface Sci. 209 (1989) 379] has attempted to improve the agreement between our original X-ray diffraction data [Phys. Rev. Letters 54 (1985) 1275; Surface Sci. 186 (1987) 499] and the proposed distorted vacancy model by the introduction of an additional, partially occupied atom in the unit cell. Here we show that almost as much improvement can be obtained by introducing second-layer displacements into the original structure. This raises questions of uniqueness in crystallographic structure determination and the level of detail attainable without overinterpretation of data. 相似文献
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《Annals of Physics》1987,174(2):499