UHV shunt reactor for secondary arc extinction on multiphase reclosing

Secondary-arc suppression is necessary for successful fast, multiphase reclosing on UHV lines. Installation of a shunt reactor is one of the most effective methods of rapidly extinguishing the secondary arc. For multiphase reclosing on untransposed double-circuit UHV lines, a zero-sequence compensated balanced shunt reactor cannot suppress the secondary arc sufficiently. This is because of the imbalance in electrical couplings among phases. A zero-sequence compensated unbalanced shunt reactor is proposed to compensate for the imbalance in the electrostatic couplings. The effects of this reactor on suppressing the secondary arc can easily be analysed by the introduction of phase-to-phase compensation parameters. Such parameters can be used to decide on the optimum shunt reactor for secondary-arc extinction.     

Motion of an antiviral compound in a rhinovirus capsid under rotational symmetry boundary conditions

A molecular dynamics (MD) simulation of a complex of a rhinovirus protein shell referred to as a "capsid" and an anti-rhinovirus drug, WIN52084s, was performed under the rotational symmetry boundary conditions. For the simulation, the energy parameters of WIN52084s in all-atom approximations were determined by ab initio calculations using a 6-31G* basis set and the two-conformational two-stage restricted electrostatic potential fit method. The motion of WIN52084s and the capsid was focused on in the analysis of the trajectory of the simulation. The root mean square deviations of WIN52084s from the X-ray structure were decomposed to conformational, translational, and rotational components. The translation was further decomposed to radial, longitudinal, and lateral components. The conformation of WIN52084s was rigid, but moving in the pocket. The easiest path of motion for WlN52084s was on the longitudinal line, providing a track for the binding process required of the anti-rhinovirus drug to enter the pocket. The conformation of the pocket was also preserved in the simulation, although the position of the pocket in the capsid fluctuated in the lateral and radial directions.     

Effect of active oxygen species on the productivity of torularhodin by Rhodotorula glutinis No. 21

The effect of active oxygen species on the productivity of torularhodin, an effective antioxidant, by soil yeast, Rhodotorula glutinis no. 21, was examined. Methylene blue, methyviologen and AAPH [2,2'-azobis(2-amidinopropane) dihydrochloride] were used as generators of singlet oxygen, superoxide anion radicals and peroxy radicals, respectively. All of them indicated effectiveness at a dose of 1.0 x 10(-10) to 3.0 x 10(-6) M. Addition of these generators to the culture medium had almost no influence on the biosynthesis of beta-carotene, whereas it had marked enhancement on those of torulene and torularhodin. Production of uric acid by xanthineoxidase remained unchanged at a torularhodin concentration of up to 100 microM. This result suggests that torularhodin does not directly affect the productivity of superoxide anions. It has been proved that torularhodin has a more potent effect on the scavenging of peroxyl radicals and inhibits substrate degradation by singlet oxygen more effectively than beta-carotene does. Continuous addition of methylene blue enhanced the torularhodin accumulation more markedly than single addition.     

Numerical prediction of fraction of eutectic phase in Sn−Ag−Cu soldring using the phase-field method

A combination of macroscale solidification simulation and phase-field calculation is employed to predict the volume fraction of the eutectic phase in Sn-4.0 mass% Ag-XCu solder alloys (X=0.5–1.1 mass%). The solidification simulation incorporates the cooling rate in the phase-field simulation. We assume the residual liquid solidifies as eutectic phase when the driving force for the nucleation of Cu₆Sn₅ amounts to a critical value, which is determined based on the experimental data. Though the calculation results depend on the experimental data, the obtained fractions are about 40% for 0.5 mass% Cu and more than 90% for 1.1 mass% Cu alloy, which shows good agreement with the experimental data.     

A user model neural network for a personal news service

User modelling has been widely applied to pedantic situations, where we are attempting to infer the user's knowledge. In teaching it is important to know that the user has mastered the elementary concepts before proceeding with the advanced topics. However, the application of user modelling to information retrieval demands a quite different type of user model. Here we construct a user model for browsing, where the user is uncertain of exactly which information he desires. This requires a more inexact and robust user model, that can quickly give guidance to the system. We propose a user model based on neural networks that can be constructed incrementally. Performance of the model shows some promise for this approach. We discuss the advantages and limitations of the approach and its implications for user modelling.     

Digalactosyldiacylglycerol suppression of inhibition by sulfoquinovosyldiacylglycerol of alpha-glucosidase

Digalactosyldiacylglycerol (DGDG) suppressed the inhibition by sulfoquinovosyldiacylglycerol (SQDG) of an alpha-glucosidase reaction. Suppressing was considered to be an apparent decrease in inhibitory activity of SQDG ascribed to direct interaction between SQDG and DGDG. This suppression was presumed to be caused by less access of SQDG to the enzyme because SQDG and DGDG formed mixed micelles.     

Polarization Switching in (100)/(001) Oriented Epitaxial Pb(Zr, Ti)O3 Thin Films

Thin films made of (100)/(001)-oriented Pb(Zr, Ti)O₃ (PZT) were deposited by liquid-delivery metal-organic chemical vapor deposition on Ir/MgAl₂O₄/SiO₂/Si(100) substrates. For comparison, PZT thin films were also deposited on Ir/MgO(100) substrates. The X-ray scan spectra for the (202) reflections revealed that the PZT films have four-fold symmetry. It indicates that the PZT films were epitaxially grown as a cube-on-cube structure on both substrates. The switchable polarization (Q_sw) of the PZT capacitors on the silicon substrate was only 23 C/cm² at 1.8 V; however, Q_sw of PZT capacitors on MgO was 99 C/cm². In the case of PZT films deposited on silicon, the volume fraction of (001)-oriented domains (which contribute to polarization switching) was 15.1% (calculated from an XRD pattern). This result is due to the lower Q_sw of PZT capacitors on silicon. By piezoresponse-force microscopy, switchable and unswitchable domains could be identified by imaging color contrast, namely, (001) and (100) domains, respectively. Consequently, domain distribution of the PZT film on a silicon substrate indicates that the (001) domain exists in the (100) domain matrix.     

Detection of lumen-intima interface of posterior wall for measurement of elasticity of the human carotid artery

In our series of studies on noninvasive assessment of the regional elasticity of the arterial wall, the displacement gradient (change in thickness) of the arterial wall caused by the heartbeat was measured by the phased tracking method. Because the displacement gradient corresponds to the strain due to the change in blood pressure, the elasticity can be evaluated from the displacement gradient of the arterial wall and the blood pressure, which are noninvasively measured at the upper arm. In the measurement of the elasticity of the arterial wall by our method, the region in which the elastic modulus is estimated must be assigned beforehand; currently, the lumen-intima boundary of the arterial wall is manually determined by the operator. For the real-time measurement of the elasticity of the arterial wall, a fast, automated method is necessary for detection of the boundary. In this paper, a cost function is proposed for differentiation of the arterial wall from the lumen. The proposed cost function was applied to ultrasound data, which were noninvasively obtained for five human carotid arteries. In comparison with the case of detection using only the amplitude of the echo, the root mean square error between the automatically detected lumen-intima boundary and the manually assigned boundary was significantly improved by using the proposed cost function. Furthermore, the lumen- intima boundary was automatically detected in a short period. Such a method is required for real-time measurement of the elasticity of the arterial wall, though detection of the outer boundary of the adventitia, which is not described in this paper, is also necessary to realize real-time elasticity measurement by our method.     

A stochastic method to predict the consequence of arbitrary forms of spike-timing-dependent plasticity

Synapses in various neural preparations exhibit spike-timing-dependent plasticity (STDP) with a variety of learning window functions. The window functions determine the magnitude and the polarity of synaptic change according to the time difference of pre- and postsynaptic spikes. Numerical experiments revealed that STDP learning with a single-exponential window function resulted in a bimodal distribution of synaptic conductances as a consequence of competition between synapses. A slightly modified window function, however, resulted in a unimodal distribution rather than a bimodal distribution. Since various window functions have been observed in neural preparations, we develop a rigorous mathematical method to calculate the conductance distribution for any given window function. Our method is based on the Fokker-Planck equation to determine the conductance distribution and on the Ornstein-Uhlenbeck process to characterize the membrane potential fluctuations. Demonstrating that our method reproduces the known quantitative results of STDP learning, we apply the method to the type of STDP learning found recently in the CA1 region of the rat hippocampus. We find that this learning can result in nearly optimized competition between synapses. Meanwhile, we find that the type of STDP learning found in the cerebellum-like structure of electric fish can result in all-or-none synapses: either all the synaptic conductances are maximized, or none of them becomes significantly large. Our method also determines the window function that optimizes synaptic competition.     

Optimal boiler control through real-time monitoring of unburned carbon in fly ash by laser-induced breakdown spectroscopy

A laser-induced breakdown spectroscopy (LIBS) technique has been applied for detection of unburned carbon in fly ash, and an automated LIBS unit has been developed and applied in a 1000-MW pulverized-coal-fired power plant for real-time measurement, specifically of unburned carbon in fly ash. Good agreement was found between measurement results from the LIBS method and those from the conventional method (Japanese Industrial Standard 8815), with a standard deviation of 0.27%. This result confirms that the measurement of unburned carbon in fly ash by use of LIBS is sufficiently accurate for boiler control. Measurements taken by this apparatus were also integrated into a boiler-control system with the objective of achieving optimal and stable combustion. By control of the rotating speed of a mill rotary separator relative to measured unburned-carbon content, it has been demonstrated that boiler control is possible in an optimized manner by use of the value of the unburned-carbon content of fly ash.