The derivation of effective spin models describing the low energy magnetic properties of undoped CuO 2 –planes is reinvestigated. Our study aims at a quantitative determination of the parameters of effective spin models from those of a multi–band model and is supposed to be relevant to the analysis of recent improved experimental data on the spin wave spectrum of La 2 CuO 4. Starting from a con...

Reported is a factorization theorem for large-s behavior of total cross sections obtained in a straightforward fashion from ordinary perturbation theory. The theorem extends the standard factorization results for the Bjorken and Drell-Yan processes. The obtaining of useful evolution equations is found to be problematic. A by-product is a direct method for systematic calculations of the parton e...

Resummation, ie. reorganization of perturbative series, can result in an inconsistent perturbation theory, unless the counterterms are reorganized in an appropriate way. In this paper two methods are presented for resummation of counterterms: one is a direct method where the necessary counterterms are constructed order by order; the other is a general one, based on renormalization group argumen...

This paper is concerned with the problem of designing a robust adaptive controller for flexible joint robots (FJR). Under the assumption of weak joint elasticity, FJR is firstly modeled and converted into singular perturbation form. The control law consists of a FAT-based adaptive control strategy and a simple correction term. The first term of the controller is used to stability of the slow dy...

mineral dust is produced from both natural and anthropogenic sources. dust aerosols can be transported over long distances in the atmosphere. they reduce the incident shortwave radiation to the surface by absorbing and scattering the solar radiation; thereby leading to a cooling effect at the surface and lower tropospheric temperature. on the other hand, by absorption and re-emission of longwav...