We propose a simple friction model for isolated polymer chains on a solid substrate. The chains are pulled at constant velocity by one end, the other end can be trapped on the solid substrate on localised sites. We focus on the energy dissipation due to the traps. This simple model leads to non trivial friction laws, depending on the velocity and the distance between traps. Some refinements of ...

Friction originates at the area of real contact which depends on (changing) surface topography. Observing and measuring multi-asperity interfaces is difficult, making it challenging to quantitatively study interplay between frictional force In this paper, we systematically manipulate topography use a fluorescence microscopy-based visualization technique reveal interplay. We demonstrate good agr...

Planning t>he motion of bodies in cont,act requires a model of contact rnechanics in order to predict sliding, rolling, and jamming. Such a model t'ypi-cally includes estimates of the coefficients of friction. Though, usually assumed t,o be constant, these coefficients vary and are difficult to measure. In this paper, we treat, the coefficient,s of friction as independent variables and derive r...

This paper develops a model to assess the quantitative effect of entry cost and financial friction on cross-country income and total factor productivity (TFP) differences. The main focus is on the interaction between entry cost and financial friction. The model is calibrated to match establishment-level statistics for the U.S. economy assuming a perfect financial market. The quantitative analys...

We discuss a piecewise-conserved constant of motion for a simple dissipative oscillatory mechanical system. The system is a harmonic oscillator with sliding (dry) friction. The piecewise-conserved constant of motion corresponds to the time average of the energy of the system during one halfperiod of the motion, and changes abruptly at the turning points of the motion. At late times the piecewis...

1. Six men and four women, 30-51 yr of age, were asked to use the tip of the washed and dried index finger to stroke six different featureless, flat surfaces mounted on a three-dimensional force platform. The six surfaces were rosin-coated glass, glass, satin-finished aluminum, poly-vinyl chloride (PVC) plastic, Teflon, and nyloprint (polyamide plastic). The subjects were requested to indicate ...

The effect of a height-dependent asperity radius of curvature is accounted for in a recently developed scaledependent model of contact and friction. The contact and friction model includes the effects of adhesion, using the Maugis model, and of scale-dependent friction, using the Hurtado and Kim single asperity friction model. This multiasperity model has been modified to include the effect of ...

The major losses of fluid flow in plastic pipes due to friction are usually few or negligible some cases, and this is the assumption that value factor small (small roughness). This work aimed estimate vs Reynolds number compared against previous data, was estimated using an experimental model consisting a polypropylene pipe with nominal outside diameter 16mm length 8.5 meter eighteen elbows con...

Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (superChandrasekhar) dynamical friction, after which they experience no dynamical friction at all. For density profiles with a central power law profile, ρ ∝ r−α, the infalling satellite heats the background and causes α to decrease. For...

this paper presents the new topology of three phase on line uninterruptible power supply (ups) by employing t-source inverter (tsi) with maximum constant boost pulse width modulation (pwm) control and the results are compared with the conventional uninterruptible power supply (ups). the conventional ups consists of voltage source inverter (vsi) with step up transformer or dc-dc booster which de...