This work discusses the invariance of local manipulability indices which are used to convert into a scalar the capability of a robotic device at a given configuration to perform a manipulation task. It is shown that they suffer from non–invariance in the sense that arbitrariness in the choice of the metric functions employed in their definition is unavoidable and they are not invariant under ch...

This paper addresses the kinematic sensitivity of the three degree-of-freedom 3-UPU parallel mechanism, a mechanism consisting of a fixed base and a moving platform connected by three serial UPU chains. Although a mathematical mobility analysis confirms that the mechanism has three degrees of freedom, hardware prototypes exhibit unexpected large motions of the platform even when the three prism...

An examination of the positions and redshifts of the compact, QSO-like objects reported near the Seyfert 2 galaxy NGC 1068 has revealed many relationships that suggest strongly that the objects have been ejected from the galaxy. Although some of the same relations have been found for the compact objects near NGC 3516, the higher number of sources near NGC 1068 has resulted in a detailed physica...

This article presents an extension of works by Olivier Faugeras and Th eo Papadopoulo on moving 3D curves. They have developed a theory for the motion elds of 3D curves seen in a monocular sequence of 2D images and described methods for computing the kinematic screw (; V) of the curve and its time derivative (_ ; _ V) in the case of rigid 3D motion. Here the results of implementing one of these...

This note deals with two-mechanism models (= 2M models). 2M models (or, generally, multimechanism models) are a useful tool for modelling of complex material behavior. They have been studied and applied for the last twenty years. This note is focused on the modelling of 2M models in continuum-mechanical framework mainly in the case of plastic behaviour. In particular, some classes of 2M models ...

The paper discusses the kinematics of manipulators builts of planar closed kinematic chains. A special kinematic scheme is extracted from the array of these mechanisms that looks the most promising for the creation of different types of robotic manipulators. The structural features of this manipulator determine a number of its original properties that essentially simplify its control. These fea...

Magnetic helicity fluxes are investigated in a family of gauges in which the contribution from ideal magnetohydrodynamics takes the form of a purely advective flux. Numerical simulations of magnetohydrodynamic turbulence in this advective gauge family exhibit instabilities triggered by the build-up of unphysical irrotational contributions to the magnetic vector potential. As a remedy, the vecto...

This study is part of a larger project investigating the individual and combined effects of word position, utterance length, and phonetic context on kinematic aspects of labial and mandibular movements during grammatically correct and semantically meaningful utterances. In the present study, the effects of word position and utterance length on kinematic measures of movement duration, movement e...