Parallel processing of network calculations in order to speed up transient stability analysis

Power systems have become very large, and in addition the forthcoming open electricity market will make power system operation more complex. Therefore, power system operation must become more efficient and flexible. Very fast power system simulation is a means of achieving more sophisticated power system on‐line monitoring and control, and parallel computing is a key technology for very fast power system simulation. This paper proposes an efficient and fast parallel network calculation algorithm that will contribute to the development of fast power system simulation programs. Numerical examples show that the proposed method using six processors is about 4.0 times as fast as the usual serial algorithm when applied to a large‐scale radial power system and about 3.2 times as fast when applied to a large‐scale loop power system. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 26–36, 2001     

A 250-Mb/s/pin, 1-Gb double-data-rate SDRAM with a bidirectionaldelay and an interbank shared redundancy scheme

This paper describes three circuit technologies indispensable for high-bandwidth multibank DRAM's. (1) A clock generator based on a bidirectional delay (BDD) eliminates the output skew. The BDD measures the cycle time as the quantity charged or discharged of an analog quantity, and replicates it in the next cycle. This achieves a 0.18-mm ², two-cycle-lock clock generator operating from 25 to 167 MHz with a 30-ps resolution. (2) A quad-coupled receiver eliminates the internal skew caused by the difference between a rise input and a fall input by 40%. (3) An interbank shared redundancy scheme (ISR) with a variable unit redundancy (VUR) efficiently increases yield in multibank DRAM's. The ISR allows redundancy match circuits to be shared with two or more banks. The VUR allows the number of units replaced to be variable. These circuit technologies achieved a 250-Mb/s/pin, 8-bank, 1-Gb double-data-rate synchronous DRAM     

Synthesis temperature of Ba4CuPt2O9 compounds and the influence of their addition on the orientation of the c-axes of fluorine-doped YBCO superconductors

An experimental study has been carried out to investigate the synergistic effect of Ba₄CuPt₂O₉ compounds on the critical current density of fluorine-doped YBCO superconductors. The Ba₄CuPt₂O₉ compounds were synthesized by a solid state reaction. It was found that the synthesis temperature of the Ba₄CuPt₂O₉ compounds was over 800°C, which was higher than that ever reported previously. In addition, the influence of Ba₄CuPt₂O₉ compounds on the critical current density of YBCO superconductors has been investigated using two types of Ba₄CuPt₂O₉ compounds: one is not heat-treated, i.e. source materials; and the other is heat-treated at 950°C. It was found that the former affected the orientation of the c-axes, but the latter did not have an influence on the orientation of the c-axes, but adversely affected the superconductivity of samples quenched at temperatures above 850°C.     

Hemarthrosis of the knee and bone contusion

The displacement of porcine [125I] insulin bound to rat and lamprey isolated hepatocytes with unlabeled lamprey and porcine insulins was investigated. Binding affinity of lamprey insulin for insulin receptor of rat was similar to that of porcine insulin. In contrast, the binding affinity of lamprey insulin for its own insulin receptor was higher than for a rat receptor. To determine the binding affinity constants of lamprey insulin receptor, the competition binding experiments were carried out on isolated lamprey hepatocytes using lamprey insulin as unlabeled ligand and tracer. The affinity of the same binding sites on lamprey hepatocytes was assessed in similar experiments but employing porcine insulin as unlabeled ligand and tracer. It was found that while Kd of low affinity binding sites on lamprey hepatocytes were similar for lamprey and porcine insulins, the Kd of high affinity binding sites was different: the displacement curve for lamprey insulin being shifted to the left as compared to the curve for porcine insulin. The number of high and low affinity binding sites, calculated independently in Scatchard plots, was equal. We conclude that the high affinity insulin binding sites of lamprey but not of rat hepatocytes reveal some species specificity in ligand-receptor interaction.     

Accelerated Discovery of Potent Bioactive anti-TNFα Aptamers by Microbead-Assisted Capillary Electrophoresis (MACE)-SELEX

Dysregulation of tumor necrosis factor-α (TNFα), a pro-inflammatory cytokine, causes several diseases, making it an important therapeutic target. Here, we identified a novel DNA aptamer against human TNFα using in vitro selection, which included a high exclusion pressure process against non-binding and weak binders through microbead-assisted capillary electrophoresis (MACE) in only three rounds. Among the 15 most enriched aptamers, Apt14 exhibited the highest inhibitory activity for the interaction between TNFα and its cognate receptor in mouse L929 cells. For further improving the bioactivity of the aptamer, dimerization programed by hybridization was evaluated, resulting in the Apt14 dimer exhibited a twofold higher binding affinity and stronger inhibition compared to the monomer counterpart. Rapid identification of bioactive aptamers using MACE in combination with facile dimerization by hybridization accelerates the discovery of novel bioactive aptamers, paving the way toward replacing current monoclonal antibody therapy with the less expensive and non-immunogenic aptamer therapy.     

Hydrogen isotope permeation from cooling water through various metal piping

In order to investigate the behavior of hydrogen isotope on the water–metal boundary, deuterium permeation experiments from heavy water vessel through various metal piping, such as pure iron (Fe), nickel (Ni), stainless steel (SS304), and pure iron with 10 μm gold plating, were performed at 573 K and at 15 MPa. During the experiment, surfaces of metal piping except gold plating one were oxidized at the heavy water boundary and then deuterium would generate by the oxidation reactions. This deuterium could be detected by mass spectrometer, which monitored the inside gases of the piping under continuous evacuation. The result showed clearly that the deuterium permeated through Fe, Ni, and SS304 piping was detected as mainly deuterium gas (D₂) under continuous evacuation, though that through gold plating one could not be detected effectively. The D₂ permeation rate through Fe, Ni, and SS304 piping reached equilibrium conditions with oxide generation at D₂O–metal boundary, although concluding the transfer mechanism will require further testing and modeling activities.     

Response function estimation with fine energy bins for the energy-resolved computed tomography using a transXend detector

A new ‘transXend’ detector system has been developed for energy-resolved computed tomography (CT). It consists of several segmented detectors that measure X-rays as electric currents. Response functions of segmented detectors are estimated using component materials of a body under inspection to unfold X-ray spectra. To avoid material-dependent measurements, response functions inherent to segmented detectors are evaluated by Monte Carlo calculations. CT was performed for a phantom consisting of five resins and was analyzed by the estimated response functions. The linear attenuation coefficients for the five resins have excellent agreement with database values.     

Performance improvement of the filter-type ‘transXend’ energy-resolving detector by considering noise sensitivity

The filter-type ‘transXend’ detector is an energy-resolving X-ray detector consisting of an energy-integrating flat-panel detector and multiple filters. In our previous studies, we have shown the effectiveness of the transXend detector, but the filters used were not optimized. To obtain better performance, the filters, especially their thickness and material, should be considered. In this paper, we present a method that can preliminarily estimate filter performance by comparing their noise sensitivity before carrying out numerous experiments. Two kinds of filter sets, Cu–Sn and W–Ag, with various thicknesses were evaluated. The results suggest that to image a 20-cm-thick object with 120-kV X-rays, an unfiltered channel and a channel filtered with 0.5-mm-thick Sn or 0.4-mm-thick Ag may be the best combination. The optimal filter thickness will be smaller if the object is thinner and the tube voltage is lower. For applications that require a wide dynamic range of detector response, a channel with a W filter may be better than an unfiltered channel. To verify the calculation results, computed tomography imaging experiments with a 3-cm-diameter phantom were also performed, and the experimental results showed good agreement with the calculation results.     

A feasible core design of lead bismuth eutectic cooled CANDLE fast reactor

Among the innovative reactor concepts, CANDLE has several advantages over conventional reactor designs. However, when CANDLE is extended to long life, the clad integrity at high neutron fluence, the build-up of fission product gases, and the pressure drop for long cores pose technological challenges which have to be overcome. In this paper, we propose practically viable design procedures, such as recladding the entire fuel pins and replacement of different amounts of fuel at different radial positions, to ensure clad integrity and flat power distribution, respectively. We demonstrate the efficacy of such design procedures by calculations that are performed on a LBE CANDLE reactor. Our calculations show that for a reactor operation period of 3700 days the various reactor parameters are within the limits proposed by Japan Atomic Energy Agency (JAEA).     

Compatibility of erbium oxide coating with liquid lithium–lead alloy and corrosion protection effect of iron layer

Li–Pb compatibility of Er₂O₃ and Er₂O₃-Fe two-layer coatings has been explored for an understanding of corrosion behaviors and effects of the protection layer. The coatings were peeled off after static Li–Pb immersion test at 600 °C due to the degradation of adhesion between the coating–substrate interface. A loss of Er and then subsequent corrosion of Er₂O₃ were shown after immersion at 500 °C for 500 and 1505 h. However, the outer Fe layer played a role to decrease corrosion rate of the coatings by comparing with the results of Er₂O₃ single layer coatings. Deuterium permeation measurements after corrosion tests at 500 °C showed that the Er₂O₃ coatings kept permeation reduction factors of 10²–10³ after 500 h immersion, but seriously degraded after 1505 h immersion. Corrosion mechanisms suggest that corrosion protection properties will be modified by an optimization of the outer Fe layer and a control of oxygen concentration in Li–Pb.