RESUMEN
A two-tank multivariate loop was designed and built to support research related to instrumentation and control, equipment and sensor monitoring. This test bed provides the framework necessary to investigate and test control strategies and fault detection methods applicable to sensors, equipment, and actuators, and was used to experimentally develop and demonstrate a fault-tolerant control strategy using six correlated variables in a single-tank configuration. This work shows the feasibility of using data-based empirical models to perform fault detection and substitute faulty measurements with predictions and to perform control reconfiguration in the presence of actuator failure in a real system. These experiments were particularly important because they offered the opportunity to prove that a system, such as the multivariate control loop, could survive degraded conditions, provided the empirical models used were accurate and representative of the process dynamics.
RESUMEN
The intestinal absorption of sodium taurocholate was studied in fetuses, neonates, infants, children, and adults. Absorption rates were measured in vitro in everted rings of jejunum and ileum. Mucosal accumulation of 3H-taurocholate against a concentration gradient was consistently demonstrated in rings of ileum from adults, children, and infants older than 8 months, whereas fetal and neonatal ileal mucosal concentrations were not significantly above those in the incubation medium after exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. There were no significant differences in mucosal uptake of taurocholate by perinatal jejunal and ileal rings. Incubations of mucosa from older infants, children, and adults in 0.3 mM taurocholate exhibited saturation phenomena. It is concluded that the ileal mechanism for active transport of taurocholate is undeveloped in the fetus and newborn infant. It is probable that the enterohepatic circulation of bile salt during the perinatal period is limited to that fraction of bile salt absorbed passively. The results suggest that losses of bile salt from the immature intestine may contribute to the steatorrhea and so-called diarrhea of newborn infants.