1. Three men and seven women, 25-40 yr of age, were asked to use the thumb and index fingers to grasp, lift, and hold the armature of a linear motor generating a 2.0-N opposing force (simulating an object weighing approximately 200 g) for 2 s. The surface in contact with the fingers was composed of smooth or polyamide plastic etched with 1.0-mm high Braille beads separated at 2.0- or 3.0-mm int...

The tribology of lubricated poly(ether ether ketone) (PEEK)—steel tribosystems was investigated in the static and boundary friction regime. Pentaerythrite ester and trimellitic acid ester were used as lubricants. The lubricants differed in their molecular structure but showed only minor differences in their rheological and cohesive energetic properties. In order to investigate the effect of the...

We generalize a model for friction at a sliding interface involving the motion of misfit dislocations to include the effect of thermally activated transitions across barriers. We obtain a comparatively simple form with the absolute zero-temperature Peierls barrier replaced by an effective Peierls barrier which varies exponentially with temperature, in agreement with recent experimental observat...

In this paper, a control scheme for emergency braking maneuvers in automated highway systems (AHSs) and a new online identification scheme to determine the tire–road friction characteristics of the vehicle are presented. The proposed controller determines the required pressure in the master cylinder of the braking system to achieve maximum deceleration during braking, based on the estimation of...

This study investigated the friction between surgical instruments and bone to aid improvements to instrument design. The bases of orthopaedic surgical instruments are usually made of metal, especially stainless steel. Silicone elastomer was chosen as an alternate biocompatible material, which would be compliant on the bone surface when used as the base of an instrument. The coefficient of stati...

The stick-to-slip transition of a fingertip in contact with a planar surface does not occur instantaneously. As the tangential load increases, portions of the skin adhere while others slip, giving rise to an evolution of the contact state, termed partial slip. We develop a quasi-static model that predicts that if the coefficient of kinetic friction is larger than the coefficient of static frict...

This study investigated the relationship of required coefficient of friction to gait speed, obstacle height, and turning strategy as participants walked around obstacles of various heights. Ten healthy, young adults performed 90° turns around corner pylons of four different heights at their self selected normal, slow, and fast walking speeds using both step and spin turning strategies. Kinetic ...

We use the existing data of force-extension experiments on F-actin molecules tied into knots to compute a value of 0.15 for the static friction coefficient for contact between different parts of the same molecule with itself. This estimate for protein-protein friction is relevant for the stabilization of the 273 known proteins with knots, one percent of the structures deposited in the Protein D...

We study, using fluorescence correlation spectroscopy, translational diffusion in molecularly thin liquids confined within a surface forces apparatus. The diffusion coefficient decreases exponentially from the edges towards the center of the Hertzian contact and further suggests the presence of a small number of distinct diffusion processes. This holds alike a crystallizable fluid (OMCTS) and a...

physical properties of four common iranian varieties of canola seeds (hyola, okapi, orient and slm) were evaluated as a function of their moisture contents. the average seed length and thousand seed mass varied linearly from 1.925 to 2.262 mm and from 3.06 to 4.84 g, respectively. the average diameter, geometric mean diameter, and sphericity varied non-linearly from 1.475 to 1.911 mm, 1.625 to ...