In this paper, we address the stiffness synthesis problem of variable geometry double planar parallel robots. For a desired stiffness matrix, the free geometrical variables are calculated as a solution of a corresponding polynomial system. Since in practice the set of free geometrical variables might be deficient, the suggested solution addresses also the case where not all stiffness matrix ele...

A unilaterally constrained perturbed double double integrator system is studied in this paper. The aim is to establish uniform finite time stability of the non-linear dynamics in the presence of impacts due to the constraints on the position variable. A non-smooth transformation is utilized to first transform the system into a variable structure system that can be studied within the framework o...

We show that recent data from HERA on the proton structure function F2 at small x and large Q 2 provide a direct confirmation of the double asymptotic scaling prediction of perturbative QCD. A linear rise of lnF2 with the scaling variable σ is observed throughout the kinematic region probed at HERA, and the measured slope is in excellent agreement with the QCD prediction. This provides a direct...

We propose a new variable, Rj , in order to identify exclusive double-diffractive high ET dijet production. The variable Rj is calculated using the transverse energy ET and pseudorapidity of the jet with the largest ET . For a purely exclusive event the value of Rj → 1, if we were to neglect hadronisaton and the detector resolution effects. To illustrate the expected Rj-distribution we also com...

Ecole normale sup erieure de Paris Given a family of nite dimensional statistical models and a nite number of observations of a random variable, we show how to build a \double mixture" estimator for the density of the random variable whose risk in terms of Kullback-Leibler divergence has a sharp bound compared to the risk of the best model in the family. This estimator is a mixture of model est...

Melanocytes, the pigment-producing cells, arise from multipotent neural crest (NC) cells during embryogenesis. Many genes required for melanocyte development were identified using mouse pigmentation mutants. The variable spotting mouse pigmentation mutant arose spontaneously at the Jackson Laboratory. We identified a G-to-A nucleotide transition in exon 3 of the Ets1 gene in variable spotting, ...