Development of a Data-Based Method for Performance Monitoring of Heat Exchangers

A multivariate analysis method is developed for processing measurements, and for detecting and isolating faults and monitoring performance degradation in heat exchanger control loops. A heat exchanger inside a typical temperature to flow cascade loop is considered. This system includes a constant speed pump with flow control valves, pressure and temperature measurement. A proportional-integral-differential (PID) controller is used to maintain a temperature set point for the exit flow on one side of the exchanger. A thermal-fluid model for the components in the system is developed. A Fault Detection and Isolation (FDI) rule-base is formulated from results of simulations performed using these models. Measurements from an installed laboratory heat exchanger control loop are also used. Faults simulated and induced on the physical heat exchanger loop include tube fouling, sensor drift, fluid leakage, unresponsive valves, plugged process lines, and controller errors. The rule base allows the identification of faults in a heat exchanger control loop given suitable process measurements

LIVER DELTA-AMINOLEVULINATE DEHYDRATASE ACTIVITY IN AMITRIPTYLINE-TREATED OR CHLORPROMAZINE-TREATED RATS

Amitriptyline (AMT) and chlorpromazine (CPZ) (0.5 mg per animal, i.p.) were injected into rats separately for 30 days and their effects on heme metabolism in liver were examined. Significant decreases in the delta-aminolevulinate dehydratase activity were observed following the administration of both drugs (mean value of AMT-group: 6.58 U/g tissue; and CPZ-group: 7.04 U/g tissue) in comparison to that of controls (11.71 U/g tissue); however total liver heme content was not altered. When 24-h urinary excretions of delta-aminolevulinate (ALA) and porphobilinogen (PBG) were measured on the last day of the experiment, a slight (AMT-group: 38.40 mug/day) to distinct (CPZ-group: 59.11 mug/day) increase of urinary ALA was observed, while PBG excretion tended to decline only moderately under CPZ (3.52 mug/day), but significantly in presence of AMT (2.16 mug/day). Mean values obtained from control group were 32.12 mug/day for ALA and 4.25 mug/day for PBG

Hybrid digital signal processing and neural networks applications in PWRs

Signal validation and plant subsystem tracking in power and process industries require the prediction of one or more state variables. Both heteroassociative and auotassociative neural networks were applied for characterizing relationships among sets of signals. A multi-layer neural network paradigm was applied for sensor and process monitoring in a Pressurized Water Reactor (PWR). This nonlinear interpolation technique was found to be very effective for these applications

Hybrid digital signal processing and neural networks applications in PWRs

Signal validation and plant subsystem tracking in power and process industries require the prediction of one or more state variables. Both heteroassociative and auotassociative neural networks were applied for characterizing relationships among sets of signals. A multi-layer neural network paradigm was applied for sensor and process monitoring in a Pressurized Water Reactor (PWR). This nonlinear interpolation technique was found to be very effective for these applications

RELATIONSHIP OF MATERNAL AND FETAL PLASMA ASCORBIC-ACID LEVELS TO OCCURRENCE OF PREMATURE RUPTURE OF MEMBRANES

Low levels of blood ascorbate in pregnant women had been thought to have a role in incidence of premature rupture of membranes (PROM). In this study, maternal and fetal blood levels of ascorbate were surveyed in term and preterm labor. Each group was subdivided according to the presence of PROM. Placental ascorbate levels were also studied. Since ascorbate is known to be involved in the synthesis of collagen, hydroxyproline content of the amnion was also measured and taken as an index for collagen production. Amnionic membranes from births with PROM showed relatively low levels of hydroxyproline. Preterm newborns with PROM also exhibited a significantly low ascorbate concentration as compared with preterm controls. In conclusion, ascorbate in the fetal compartment appears to be important for the occurrence of PROM