This study formulates a universal velocity ®eld that is kinematically admissible for application in the extrusion of non-axisymmetric rods. Then upper bound theorem dictates that a better upper bound solution heavily depends on the precise conformity of the velocity ®eld postulated. However, a compromise must frequently be made, since the formulation is in general rather complicated. The kinema...

We investigate theoretically a novel mechanism of transducing chemical energy into a directed force. A hypothetical motor protein is considered such that conformational changes induced by nucleotide binding and/or hydrolysis lead to asymmetric internal velocity uctu-ations. We demonstrate that these uctuations result in unidirectional motion if rectiied by protein friction. The motor protein fo...

We examine the performance of several methods to estimate meteorological 1 inputs for modelling dispersion in urban areas during convective conditions. Sensible heat 2 flux, surface friction velocity and turbulent velocities are estimated from measurements of 3 mean wind speed and the standard deviation of temperature fluctuations at a single level on a 4 tower at two suburban sites and at one ...

We consider motion on the circle, possibly with friction and external forces, the initial velocity being a large random variable. We prove that under various assumptions the distribution of the stopping position of the motion converges to a distribution depending only on the motion equation. Here the time of stopping is either a constant or the rst time instant at which the velocity vanishes, a...

in the present paper, an analysis was carried out to investigate effects of radiation on a free convection flow bounded by a vertical surface embedded in a porous medium with constant suction velocity. it was under the influence of uniform magnetic field in the presence of a homogenous chemical reaction and viscous dissipation with constant heat and mass flux. the non-dimensional governing equa...

this paper proposes an efficient tracking method for velocity control of an electro-hydraulic servo system (ehss) in the presence of flow nonlinearities and internal friction. the tracking method controller is a kind of feedback error learning structure. in the proposed method, the feedback error learning (fel) algorithm is used to control the velocity. there is no need to compute the system ja...

It is well known that classical Coulomb dry friction model does not portrays important physical phenomena occurring in the contact between mating surfaces. Moreover, the discontinuity of force at zero velocity has many drawbacks during numerical simulations. In the attempt of exploring alternatives to Coulomb friction model, this paper present the application of the Dahl friction model in a mul...

Laterally asymmetric vibrotactile stimuli produce anisotropic or direction-dependent friction force that function as a friction display system [1]. In this study, we showed that laterally symmetric vibrotactile stimuli increase friction perception by a similar principle. We measured the frictional forces between a sliding finger pad and a contactor laterally vibrating at 3 or 5 H. We found that...

The development of Scanning Force Microscopy has provided us with tools to study friction and wear on the nanometer scale. The atomic granularity of matter shows up in the lateral force which is necessary to slide a small contact over a flat surface. Also, mechanical damage of a sample surface can be monitored with monolayer resolution [1]. The laws which determine the dependence of friction on...

In the general framework of tracking control of hydraulic servo systems, this paper presents a comparison between two main possibilities to include friction information in the picture: experimental identification and estimation. Experiments were first conducted in order to find a suitable representation for friction in the system. We then looked at two observers reported in the literature (know...