Expert systems for emergency alarms analysis during accident situations in nuclear reactors

Expert system development is an important application of artificial intelligence. During the last few years, many successful expert systems have been developed in various fields like medical diagnosis, geological exploration, office management, etc. Expert systems is a computer software which solves reasonably complex problems where normally one needs an expert in that field to solve them.Recently efforts are being made in developing expert systems to support the operating staff in nuclear reactors. Nuclear power plant is one of the most complex engineering systems and safe and reliable operation is of primary importance. In spite of many automatic and redundant safety systems there are some occasions when the operating staff have to analyse the alarms and take further safety actions. Few of the severe accidents like Three Mile Island in USA and Chernobyl in USSR are attributed to the errors made by the operating staff and/or management. Nuclear engineers or systems analysts who may be expert in analysing an accident situation and advise corrective safety actions may not be readily available during the accident situations in the nuclear power plants. It is possible to model such expert knowledge in expert systems and this can be applied in diagnosing an accident situation like the loss of coolant accident (LOCA) and act as an additional confirmatory aid to the operating staff.Two small expert systems examples have been developed and are explained in this paper. One identifies a spurious LOCA alarm in a heavy water research reactor. The second example identifies the type of medium/small leakage (LOCA) in a coolant circuit of a PWR and suggests the subsequent safety actions. Both the examples have been developed using the expert systems shell VP-expert. They are off-line usable and user interactive. We do not propose expert system application for very fast response safety actions like reactor scram. These two small expert system examples are essentially to support the feasibility study in their applications during accident situations in nuclear power plants.     

Brain Metastases from Lung Cancer Show Increased Expression of DVL1, DVL3 and Beta-Catenin and Down-Regulation of E-Cadherin

The susceptibility of brain to secondary formation from lung cancer primaries is a well-known phenomenon. In contrast, the molecular basis for invasion and metastasis to the brain is largely unknown. In the present study, 31 brain metastases that originated from primary lung carcinomas were analyzed regarding over expression of Dishevelled-1 (DVL1), Dishevelled-3 (DVL3), E-cadherin (CDH1) and beta-catenin (CTNNB1). Protein expressions and localizations were analyzed by immunohistochemistry. Genetic alterations of E-cadherin were tested by polymerase chain reaction (PCR)/loss of heterozygosity (LOH). Heteroduplex was used to investigate mutations in beta-catenin. DVL1 and DVL3 showed over expression in brain metastasis in 87.1% and 90.3% of samples respectively. Nuclear staining was observed in 54.8% of cases for DVL1 and 53.3% for DVL3. The main effector of the Wnt signaling, beta-catenin, was up-regulated in 56%, and transferred to the nucleus in 36% of metastases. When DVL1 and DVL3 were up-regulated the number of cases with nuclear beta-catenin significantly increased (p = 0.0001). Down-regulation of E-cadherin was observed in 80% of samples. Genetic analysis showed 36% of samples with LOH of the CDH1. In comparison to other lung cancer pathologies, the diagnoses adenocarcinoma and small cell lung cancer (SCLC) were significantly associated to CDH1 LOH (p = 0.001). Microsatellite instability was detected in one metastasis from adenocarcinoma. Exon 3 of beta-catenin was not targeted. Altered expression of Dishevelled-1, Dishevelled-3, E-cadherin and beta-catenin were present in brain metastases which indicates that Wnt signaling is important and may contribute to better understanding of genetic profile conditioning lung cancer metastasis to the brain.     

A label-free DNA sensor based on impedance spectroscopy

This paper describes a label-free detection system for DNA strands based on gold electrodes and impedance measurements. A single-stranded 18 mer oligonucleotide (ssDNA) was immobilised via a thiol linker on gold film electrodes and served as probe DNA. Residual binding places were filled with mercaptobutanol. The sensor surface clearly distinguished between complementary and non-complementary target ssDNA. Additionally, detection of single base pair mismatches was possible. The electrode was impedimetrically characterised in the presence of the redox system ferri/ferrocyanide before and after DNA hybridisation. Impedance analysis showed that the charge transfer resistance, R_ct, was increasing after DNA duplex formation, whereas the capacitive properties remain rather unaltered. The relative change of R_ct was used as sensor parameter. Concentrations in the nanomolar range have been detected by the system. The sensor was reusable because a denaturation protocol allowed effective double strand dissociation without changing the surface properties of the electrode substantially. The time for DNA detection have been reduced to about 15 min including regeneration. The sensor signal was amplified by about 20% after binding of a negatively charged molecule to the formed DNA duplex. The sensor was also capable of sensing longer target ssDNA strands as shown with 25 mer and 37 mer oligonucleotides.     

Group delay measurements of optical components near 800 nm

Phase-locked interferometry was used to measure the group delay of several optical components in the spectral region 700-850 nm. The dispersive and absorptive properties of several different types of linear filters were measured. Measurements of the absorption and dispersion of several linear, causal optical filters show that a generalized Kramers-Kronig relation does not exist for many commonly used filters. This result emphasizes the importance of making direct measurements of the dispersive properties of filters, since the dispersion of a linear filter cannot always be determined from a measurement of its absorption. Data are presented for a birefringent filter, dielectric mirror, Gires-Tournois interferometer, and titanium-doped sapphire     

Picosecond and femtosecond pulse generation in a regenerativelymode-locked Ti:sapphire laser

The authors have produced transform-limited pulses ranging from 100 ps to 40 fs duration from a Ti:sapphire laser. Output powers in excess of 1 W and peak powers of 0.5 MW have been observed. They describe the technique of regenerative mode locking and present evidence that a transient with a peak power of more than 10 kW is required to initiate mode locking. The role of group velocity dispersion is highlighted and a value of -750 fs² is measured for the group delay dispersion in an operating laser. The authors describe the limits on both the power and pulsewidth obtainable from this laser and present pulse compression experiments which produce 17 fs pulses with 70 mW of average power     

Integration of remote measurement calibration with stateestimation-a feasibility study

The authors describe the integration of measurement calibration and state estimation methodologies for increasing the confidence level in a real-time database. The objectives are to improve performance of state estimators and to reduce the system engineering effort which goes into its installations and the related measurement calibrations. These objectives are accomplished by remotely minimizing the systematic errors and providing the state estimator with zero-mean and the actual standard deviation for each measurement. The state estimator is then able to suppress the spurious errors and furnish a dependable real-time database for the computer control of power systems. The approach was supported by experimental results carried on a 55 bus portion of an actual power system     

Design, construction, implementation, and cost of a hospital pharmacy cleanroom

The authors sought to clarify in a cross-sectional study the possible associations between homeostatic regulators of calcium and occupational exposure to lead. Subjects were 146 industrial male employees, 56 with and 90 without occupational lead exposure. The main outcome measures were serum concentration of parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (calcitriol). The median values of blood lead were 40.5 microg/dl in the exposed group and 4.0 microg/dl in the controls. There were no differences between groups in dietary history and serum calcium levels. PTH and calcitriol levels were significantly higher in the exposed than in the nonexposed subjects (42.0+/-24.2 vs. 33.6+/-14.9 pg/ml, p <0.05; and 83.8+/-27.0 vs. 67.9+/-17.6 pmol/liter, p <0.001, respectively). Multivariate analyses showed that after controlling for possible confounders, occupational lead exposure (no/yes) was independently associated with PTH level (pg/ml) (beta = 7.81, 95% confidence interval (CI) 3.7-11.5) and with calcitriol (pmol/liter) (beta = 12.3, 95% CI 3.84-20.8). It is concluded that subjects occupationally exposed to lead show a substantial compensatory increase in PTH and calcitriol activities which keep serum calcium levels within normal range. This may be of clinical significance since a sustained increase in calcitropic hormones in susceptible subjects may eventually increase the risk of bone disorders.     

Die graphische Darstellung der Leitwert-, Strom- und Leistungsverhältnisse der T-Schaltung bei konstanter Eingangsspannung und beliebiger äußerer Belastung

Ohne Zusammenfassung     

Knowledge-based systems as operational aids in power systemrestoration

The background of power system restoration is analyzed and how this process might benefit from the use of knowledge-based systems is discussed. After describing the state of the art of knowledge-based systems for power system restoration, efforts are made to review knowledge-based techniques to handle system restoration problems. The experiences of system development are reported and evaluation of the systems is addressed. Some needed technological innovations are listed that are required before knowledge-based systems can extensively be applied to power system restoration