Development of an expert system for analyzing faults in power systems based on waveform recognition by artificial neural networks

In restoration of a power system, appropriate steps need to be taken in early stages to avoid damage to the public caused by insufficient power supply. The first step in the restoration is the analysis of the fault that has produced the power failure. Today, a large amount of data will be available at the occurrence of a fault due to the use of advanced communication systems using digital relays and optical fibers. Such systems are intended to obtain data from the relays and circuit breakers (CBs) under operation and the voltage and current during operation and the prefault and postfault periods. This paper presents a hybrid fault analyzing expert system using data based on protective devices and phasor measurement. This system is a combination of an artificial neural network (ANN) and an expert system (ES). The ANN is used to simplify the analysis of current and voltage waveforms, which is considered difficult due to the presence of a fault resistance and the line impedance. Since a fault waveforms contains various ambiguous factors depending on the nature of the fault resistance, load current and other system parameters, the use of ANN is effective making such determinations.     

No requirement of reactive oxygen intermediates in Fas-mediated apoptosis

Fas is a cell surface molecule that mediates apoptosis, but the intracellular mechanisms leading to apoptosis are not well understood. It is known that diethylmaleate (DEM)-induced cell death can be blocked by substances with antioxidant activity. Here we have studied whether antioxidants have any effect on Fas-mediated apoptosis and show that they are not able to block Fas-mediated apoptosis. Therefore, it seems that reactive oxygen intermediate (ROI)-dependent and -independent mechanisms which lead to apoptosis do exist. Fas-mediated apoptosis probably proceeds via a ROI-independent pathway.     

Intrasellar meningioma: case report and review of the literature

BACKGROUND: Intrasellar meningioma is a rare clinical entity, and surgical resection may be difficult when it is hypervascularized. METHODS: A case of subdiaphragmatic hypervascular intrasellar meningioma with attachment to the dura of the anterior wall of the sella turcica is described. Literature review of 18 cases with operatively confirmed intrasellar meningioma discloses unexpected intraoperative bleeding and relatively low resectability of the tumor are also described. RESULTS: We used preoperative endovascular embolization of feeding arteries, and resected a hypervascular intrasellar meningioma by a combined transsphenoidal-transcranial approach safely and without massive bleeding. CONCLUSIONS: Preoperative endovascular embolization of feeding arteries and combined transsphenoidal-transcranial approach are useful for the surgical resection of hypervascular intrasellar meningiomas.     

Pattern replication accuracy in 1:1 synchrotron radiation lithography

The replicated pattern distortion for feature sizes down to 0.15 μm, characterized by pattern linearity, pattern density dependence, and corner rounding, is investigated in synchrotron radiation (SR) lithography. In the investigation, a highly accurate X-ray mask delineated by a focused ion beam, a chemically amplified resist, and a Fresnel diffraction model simulator are used. At a 15 μm mask-to-wafer gap, no pattern proximity effect is observed. The corner rounding radius due to Fresnel diffraction is approximately 0.04 μm.     

Thermomechanical properties,phase structure,and conductivity of organic/inorganic hybrid material filled with a conductive filler

Novel epoxy‐based organic/inorganic hybrid materials filled with carbon black (CB) were synthesized from an epoxy resin and silane alkoxide via a sol–gel process. The phase structure and thermal and mechanical properties of the hybrid materials were studied in detail. It was revealed by transmission electron microscope observations that the filled CB particles formed a secondary aggregation structure and were uniformly dispersed in the aggregate. The storage modulus in the rubbery region increased and the peak area of the tan δ curve in the glass‐transition region decreased with the hybridization of silica. Moreover, the conductive properties of the CB‐filled hybrid systems were investigated. In the same volume fraction of CB, the conductivity of the hybrid systems was much higher than that of the unmodified system. This result was attributed to the excluded volume effect of the silica network. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1980–1984, 2003     

Effects of thyroid hormone on catecholamine and its metabolite concentrations in rat cardiac muscle and cerebral cortex

The reproducibility of skin prick tests under field conditions is essential for comparing prevalences between centers in epidemiologic multicenter studies. This study aimed to evaluate and compare the reproducibility of two widely used skin prick test devices: the Multi-Test and the ALK lancet. The subjects were 28 children, aged 6-14 years, with known sensitivities to Dermatophagoides pteronyssinus (D. pter.). Both devices were applied to each subject on two occasions, 1 week apart, by different, randomly assigned fieldworkers, using histamine, negative control, and the D. pter. allergen extract. For all three tested solutions, mean wheal sizes were larger for the Multi-Test than for the ALK lancet. The coefficient of variation for histamine was 21.8% for the Multi-Test and 17.3% for the ALK lancet. The coefficients of variation for the allergen D. pter. amounted to 47.4% for the Multi-Test and to 24.6% for the ALK lancet. The percentage of concordant test results was 92.6% for the Multi-Test and 100.0% for the ALK lancet for a cutoff point of wheal size equal to or greater than 1 mm. The results of this study suggest that the single ALK lancet performs slightly better than the Multi-Test device with respect to reproducibility under conditions of epidemiologic field studies.     

Molecular characterization of tomato spotted Wilt virus defective interfering RNAs and detection of truncated L proteins

Junction sites of 25 different defective interfering (DI) RNAs of tomato spotted wilt virus (TSWV) were characterized. The DI RNAs varied in size from 2.0 to 5.2 kilobases (kb) and contained a single internal deletion. The absence of DI RNAs smaller than 2 kb suggested a size constraint for the survival of TSWV DI RNAs. This hypothesis was reinforced by the finding of a dimeric DI RNA formed by two 1.6-long monomers linked head to tail. Three types of junction sites were found, one type originating from a simple deletion; the second type contained a few extra nucleotides of unknown origin; and the third type contained a stretch of three to five nucleotides, originally occurring at both sides of the deletion and of which one was deleted. In 19 of the 25 DI RNAs studied, the original reading frame was maintained, suggesting a selective preference of DI RNAs with translational potency. Truncated proteins encoded by these DI RNAs were indeed detected in the nucleocapsid preparations. Folding studies of the complete L RNA revealed that the calculated minimal energy of folding was at 16 degreesC lower than at 23 degrees, indicating a higher stability of this molecule at low temperatures. The results suggest an involvement of locally folded secondary structures in the process of deletion, rather than the requirement of certain sequences around the deletion point. The DI RNA generation in TSWV is essentially, as discussed, similar to the process of RNA recombination described in many viruses.     

Impulse Turbine with 3D Guide Vanes for Wave Energy Conversion

In this study, in order to achieve further improvement of the performance of an impulse turbine with fixed guide vanes for wave energy conversion, the effect of guide vane shape on the performance was investigated by experiment. The investigation was performed by model testing under steady flow condition. As a result, it was found that the efficiency of the turbine with 3D guide vanes are slightly superior to that of the turbine with 2D guide vanes because of the increase of torque by means of 3D guide vane, though pressure drop across the turbine for the 3D case is slightly higher than that for the 2D case.     

Optimization of thermal processing and device design for high-efficiency c-Si solar cells

To improve the cell performance of single-crystal silicon solar cells, the process conditions have been optimized by monitoring the bulk lifetime after each thermal step in the cell fabrication process. The emitter geometry, i.e., front and rear contact size and pitch were optimized, and the cells were fabricated through a set of environmentally considered processes, especially for surface treatment, oxidation, diffusion, and electrode fabrication. Conversion efficiency of 22.3% in a 4 cm² cell, and 22.6% in a 1 cm² cell, was attained, respectively, with structural features of SiO₂ single-AR, “inverted-pyramid” fron texture, point-contact with line-emitter for front electrodes, and locally diffused BSF for rear contacts.     

Ionic liquids based on aliphatic tetraalkylammonium dications and TFSI anion as potential electrolytes

A new series of ionic liquids containing aliphatic tetraalkylammonium dications with alkyl linkage chains and TFSI anion as potential electrolytes were prepared and characterized. Some of the important physicochemical and electrochemical properties of these prepared ionic liquids, including melting point, density, solubility in common solvents, ionic conductivity, thermal and electrochemical stability, were investigated. These ammonium dicationic ionic liquids exhibited five types of phase transition behavior on heating and one stage decomposition behavior. The spacer length and the head group overall length were responsible for the solid/liquid transformation temperature, and the spacer length was more effective in lowering the solid/liquid transformation temperature than the head group overall length. The interesting findings for such dicationic ionic liquids was that they showed the lowest solid–liquid transformation temperatures among analogues with alkyl links, and belonged to the greatest thermal stable ionic liquids. The Arrhenius equation approximately described the relationship between conductivity and temperature for several prepared dicationic ionic liquids in the low temperature region studied. The electrochemical windows were about 4.3 V for C₉(N₂₂₂)₂-TFSI₂ and C₁₂(N₂₂₂)₂-TFSI₂, and 4.7 V for C₆(N₁₁₈)₂-TFSI₂ at room temperature.