This talk will introduce basic models for the behavior of polymer molecules in flow and the basic mechanisms by which viscoelasticity drives flow instabilities. We will then describe work in our group on methods for using viscoelasticity against itself, to modify flows so that they are less susceptible to instability. Development of such methods is important because many industrial coating processes are limited by the onset of flow instabilities. Finally, we illustrate the connection between the behavior of polymers in flow and the Liapunov exponents that characterize chaotic trajectories in a flow field. This connection may ultimately improve our understanding of the behavior of polymer molecules in flows with complex kinematics, as arise in porous media or turbulence.
Extrinsic motivation is responsive to rewards delivered by second parties.
Intrinsic motivation, on the other hand is inherent in the interest value of the task itself. Motivational flow is the experience of intrinsic motivation, which is in turn the result of the levels of challenge and skill involvement for a particular task. The level of flow is predictive of the amount of time a person will spend in that task, and it is though to form a basis for an individual's time allocation between occupational and leisure activities. The logs provided a time series of several hundred points for each participant, which were each subjected to nonlinear dynamical analysis through nonlinear regression. Principal results were that flow was chaotic for all participants.