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Friction is a difficult phenomenon to model and simulate. One promising friction model is the LuGre model, which captures key frictional behavior from experiments and from other friction laws. While displaying many modeling advantages, the LuGre model of friction can result in numerically stiff system dynamics. In particular, the LuGre friction model exhibits very slow dynamics during periods of sticking and very fast dynamics during periods of slip. This paper investigates the best simulation strategies for application to dynamic systems with LuGre friction. Several simulation strategies are applied including the explicit Runge-Kutta, implicit Trapezoidal, and implicit Radau-IIA schemes. It was found that both the Runge-Kutta and Radau-IIA methods performed well in simulating the system. The Runge-Kutta method had better accuracy, but the Radau-IIA method required less integration steps.

Previous studies have found that using multiple monitors increases productivity, but there are also documented drawbacks to increased monitor count and/or size. The purpose of this study was to determine whether increases in productivity hold true with newer technology, like wide flat-screens, in the multitasking context. Sixty participants were asked to complete several tasks commonly completed in an office environment. These tasks were performed on four different monitor configurations: a single and dual 17" monitor(s) and single and dual 22" monitor(s). Participants located information from several documents and compiled this information into a new document. Dependent variables measured included efficiency, effectiveness, and satisfaction. Results indicated a performance benefit for dual monitor usage, regardless of monitor size. Participants most preferred using dual 22" monitors and least preferred a single 17" monitor.

Friction is a difficult phenomenon to model and simulate. One promising friction model is the LuGre model, which captures key frictional behavior from experiments and from other friction models. While displaying many modeling advantages, the LuGre model of friction can result in numerically stiff system dynamics. In particular, the LuGre friction model exhibits very slow dynamics during periods of sticking and very fast dynamics during periods of slip. This paper investigates the best simulation strategies for application to dynamic systems with LuGre friction. Several simulation strategies are applied including the explicit Runge–Kutta, implicit Trapezoidal, and implicit Radau-IIA schemes. It was found that both the Runge–Kutta and Radau-IIA methods performed well in simulating the system. The Runge–Kutta method had better accuracy, but the Radau-IIA method required less integration steps.

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