No abstract

This artict« provides experimental data evatuaJing the applicability of a Kalman filter in quantifYing inverse heal conduction. A series of experiments was conducted using a copper plale (heal conductive medium) attached to a healer, thermocouple (temperature sensor), thermal flux meter, and signot / data acquisitWn system. Actual temperature measurements were made using this setup; then the intensity ofthermal flux was prediJ:ted using a Kalman filter with the slate variables estimation method. The predicted thermal flux vabus thus obtained were compared with the actual readings measured by the thermal flux meter. Final/y, temperatures were predicted numerically by solving direct heal conduaion problems using the predicted thermal flux as the boundary condition. The predicted temperature values thus obtained were then compared with the temperature readings from the thermocouple. A high degree of correlation between predicted and measured values is shown for both temperature and thermal flux.

No abstract

Linear stability analysis has been applied to a coextrusion fiber spinning flow that consists of a Newtonian fluid as a core layer and a Phan‐Thien/Tanner (PTT) fluid as a skin layer. These two chosen fluids show entirely different rheological behaviors. The stability of this coextrusion system was affected by the choice of three characteristic parameters: the skin layer fraction (f), the extensional parameter (ϵ), and the shear thinning parameter (ξ) in the Phan‐Thien/Tanner model. The linear stability results indicate that the viscoelastic skin layer (PTT fluid) has a stabilizing effect that delays the onset of draw resonance. Under fixed compositions (f is fixed), the stability envelopes changed from upturned curves to flattened ones as extensional force dominated the system. The neutral stable curves closed to the horizontal line at a critical draw ratio of around 20, showing similar behavior to a Newtonian fluid where the system has a very high Deborah number or it is dominated by shear thinning effects.

No abstract