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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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Research indicates that using a cell phone to talk or text while maneuvering a vehicle impairs driving performance. However, few published studies directly compare the distracting effects of texting using a hands-free (i.e., speech-based interface) versus handheld cell phone, which is an important issue for legislation, automotive interface design and driving safety training. This study compared the effect of speech-based versus handheld texting on simulated driving performance by asking participants to perform a car following task while controlling the duration of a secondary texting task. Results showed that both speech-based and handheld texting impaired driving performance relative to the drive-only condition by causing more variation in speed and lane position. Handheld texting also increased the brake response time and increased variation in headway distance. Texting using a speechbased cell phone was less detrimental to driving performance than handheld texting. Nevertheless, the speech-based texting task still significantly impaired driving compared to the drive-only condition. These results suggest that speech-based interaction disrupts driving, but reduces the levels of performance interference compared to handheld devices. In addition, the difference in the distraction effect caused by speech-based and handheld texting is not simply due to the difference in task duration.

Summary:The current study investigated age-related differences in a steering control task under low visibility conditions. Younger and older drivers were presented with displays simulating forward vehicle motion through a 3D scene of random dots on a ground plane. The lateral position of the vehicle was perturbed by a simulated side wind gust according to a sum of sinusoidal functions. The drivers' task was to steer the vehicle to maintain a straight path. The visibility of the driving scene was reduced by reducing the quantity and the quality of the optical flow field. We found that performance decreased when visibility was reduced for both older and younger drivers, with better performance for younger drivers as compared with older drivers. An age-related interaction was also found with deteriorated optical flow information. These results suggest that under reduced visibility conditions, older drivers may have increased accident risk due to decreased ability to successfully steer the vehicle.

Since its release in April 2010, the Apple iPad has become the de facto tablet for consumers. Given the increasing popularity of the iPad as a consumer, educational, and work device, we were interested in how different groups of people use the iPad. More specifically, we were interested in how students and nonstudents use the iPad at work, school, and at play. One-hundred thirteen participants completed an online survey about iPad use. Results indicated students use the iPad more often for socializing, playing games, editing and posting photos, listening to audio, and taking pictures or videos. On the other hand, nonstudents use the iPad more often for reading the news, eBooks, and eMagazines.