LetM be a compact, holomorphically symplectic Kähler manifold, and η a (1,1)-current which is nef (a limit of Kähler forms). Assume that the cohomology class of η is parabolic, that is, its top power vanishes. We prove that all Lelong sets of η are coisotropic. When M is generic, this is used to show that all Lelong numbers of η vanish. We prove that any hyperkähler manifold with Pic(M) = Z has...

Let F be an analytic diffeomorphism in (C m , 0) tangent to the identity of order n. The infinitesimal generator of F is the formal vector field X such that Exp X = F. In this paper we provide an elementary proof of the fact that X belongs to the Gevrey class of order 1/n.

This study presents a designing process for refurbishing of a 32 MW rotor-generator damaged coupling. The reason of rotor damage was being hit by the quivers of an explosion. The original coupling was union with the rotor formed after a machining process on a mono block forged rotor. In some areas imposed damages caused the breaking off and detachment of some parts in the coupling flange. Becau...

Meta-elliptical copulas are often proposed to model dependence between the components of a random vector. They specified by correlation matrix and map g, called density generator. While latter can easily be estimated from pseudo-samples observations, generator is harder estimate, especially when it does not belong parametric family. We give sufficient conditions non-parametrically identify this...

Presenting 2-generator Artin groups A(m) and braid groups B3 and B4 as towers of HNN extensions of free groups, we obtain Gröbner–Shirshov bases, normal forms and rewriting systems for these groups. c © 2005 Elsevier Ltd. All rights reserved.

A class of four-level periodic sequences derived from the binary m-sequences are presented. These sequences can be used as the training sequences in adaptive channel estimation and equalization with fast start-up for multilevel PAM or QAM transmission. The sequence generator can be implemented by simple hardware.

A nonlinear congruential pseudorandom number generator with modulus M = 2w is proposed, which may be viewed to comprise both linear as well as inversive congruential generators. The condition for it to generate sequences of maximal period length is obtained. It is akin to the inversive one and bears a remarkable resemblance to the latter.

A Monte Carlo event generator is presented. An original algorithm is developed to simulate electron–positron scattering at energies and momentum transferred much more than the electron mass. The first-order electroweak radiative corrections are included completely. Higher order corrections are taken into account by means of electron structure functions. PACS: 12.20.–m Quantum electrodynamics, 1...