BWR core internals replacement

The core shroud and other internal component (core internals) replacements were carried out at Fukushima-Daiichi unit number three of Tokyo Electric Power Company (TEPCO) in Japan. The project is the first experience of replacement procedures that have been developed for welded core shrouds and jet pumps. The outline and experience of the project are discussed in this paper.     

Ethanol and lactic acid production using sap squeezed from old oil palm trunks felled for replanting

Old oil palm trunks that had been felled for replanting were found to contain large quantities of high glucose content sap. Notably, the sap in the inner part of the trunk accounted for more than 80% of the whole trunk weight. The glucose concentration of the sap from the inner part was 85.2 g/L and decreased towards the outer part. Other sugars found in relatively low concentrations were sucrose, fructose, galactose, xylose, and rhamnose. In addition, oil palm sap was found to be rich in various kinds of amino acids, organic acids, minerals and vitamins. Based on these findings, we fermented the sap to produce ethanol using the sake brewing yeast strain, Saccharomyces cerevisiae Kyokai no.7. Ethanol was produced from the sap without the addition of nutrients, at a comparable rate and yield to the reference fermentation on YPD medium with glucose as a carbon source. Likewise, we produced lactic acid, a promising material for bio-plastics, poly-lactate, from the sap using the homolactic acid bacterium Lactobacillus lactis ATCC19435. We confirmed that sugars contained in the sap were readily converted to lactic acid with almost the same efficiency as the reference fermentation on MSR medium with glucose as a substrate. These results indicate that oil palm trunks felled for replanting are a significant resource for the production of fuel ethanol and lactic acid in palm oil-producing countries such as Malaysia and Indonesia.     

A novel quarter‐wave retardation film for improving viewing angle properties in time‐sequential stereoscopic 3D‐LCDs

We have successfully developed a quarter‐wave retardation film (QWF) for wide viewing angle 3D liquid crystal displays (3D‐LCDs) that provides high luminance, low crosstalk, low color change, and low head‐tilt‐angle dependency. It was found that the out‐of‐plane retardation (Rth) of the QWF in the LCD needs to be close to 0 nm in order to improve the 3D display properties at an off‐axis position and that the in‐plane retardation (Re) needs to be adjusted from 120 to 130 nm to achieve low color change with head tilting. We adopted a coating process for making our QWF because of its potential for retardation control. 3D‐LCDs with this QWF whose Rth was nearly zero had high performance and allowed off‐axis other than on‐axis.     

Electrochemical formation of Sm-Co alloys by codeposition of Sm and Co in a molten LiCl-KCl-SmCl3-CoCl2 system

Electrocodeposition of Sm and Co on a Cu substrate was investigated in a molten LiCl-KCl-SmCl₃ (0.5 mol.%)-CoCl₂ (0.1 mol.%) system at 723 K. Phase of the deposited Sm-Co alloys could be controlled by electrolysis potential. SmCo₃ was formed on a Cu substrate by potentiostatic electrolysis in the potential range of 0.20-0.90 V (vs. Li⁺/Li). Sm₂Co₁₇ was obtained in the potential range of 0.90-1.50 V.     

Effect of chitosan feeding on intestinal bile acid metabolism in rats

The effect of chitosan feeding (for 21 days) on intestinal bile acids was studied in male rats. Serum cholesterol levels in rats fed a commercial diet low in cholesterol were decreased by chitosan supplementation. Chitosan inhibited the transformation of cholesterol to coprostanol without causing a qualitative change in fecal excretion of these neutral sterols. Increased fiber consumption did not increase fecal excretion of bile acids, but caused a marked change in fecal bile acid composition. Litcholic acid increased sigificantly, deoxycholic acid increased to a leasser extent, whereas hyodeoxycholic acid and the 6β-isomer and 5-epimeric 3α-hydroxy-6-keto-cholanoic acid(s) decreased. The pH in the cecum and colon became elevated by chitosan feeding which affected the conversion of primary bile acids to secondary bile acids in the large intestine. In the cecum, chitosan feeding increased the concentration of α-,β-, and ω-muricholic acids, and lithocholic acid. However, the levels of hyodeoxycholic acid and its 6β-isomer, of monohydroxy-monoketo-cholanoic acids, and of 3α, 6ξ, 7ξ-trihydroxy-cholanoic acid decreased. The data suggest that chitosan feeding affects the metabolism of intestinal bile acids in rats.     

Ruthenium(IV) dioxide-catalyzed reductive gasification of intractable biomass including cellulose, heterocyclic compounds, and sludge in supercritical water

Catalytic reduction gasification in the presence of ruthenium(IV) dioxide (RuO₂) in supercritical water was used to decompose intractable biomass. The gasification of model biomass samples (glucose, cellulose, and heterocyclic compounds), and low-purity biomass samples obtained from a paper-recycling facility (paper sludge) and from a sewage treatment plant (sewage sludge) were studied. In clear contrast to another catalysts, the RuO₂ catalyst completely gasified cellulose to produce mainly hydrogen, methane, and carbon dioxide under various conditions (e.g., 673 K at 30 MPa and 773 K at 50 MPa). As for heterocyclic compounds, nitrogen compounds did not deactivate the RuO₂ catalyst; the gasification of carbazole proceeded completely. Furthermore, paper sludge was almost completely decomposed in supercritical water with RuO₂ at 723 K.     

Crystalline Phases and YAG Laser-Induced Crystallization in Sm2O3–Bi2O3–B2O3 Glasses

The glass formation region, crystalline phases, second harmonic (SH) generation, and Nd:yttrium aluminum garnet (YAG) laser-induced crystallization in the Sm₂O₃–Bi₂O₃–B₂O₃ system were clarified. The crystalline phases of Bi₄B₂O₉, Bi₃B₅O₁₂, BiBO₃, Sm _x Bi_{1− x} BO₃, and SmB₃O₆ were formed through the usual crystallization in an electric furnace. The crystallized glasses consisting of BiBO₃ and Sm _x Bi_{1− x} BO₃ showed SH generations. The formation of the nonlinear optical BiB₃O₆ phase was not confirmed. The formation (writing) region of crystal lines consisting of Sm _x Bi_{1− x} BO₃ by YAG laser irradiation was determined, in which Sm₂O₃ contents were∼10 mol%. The present study demonstrates that Sm₂O₃–Bi₂O₃–B₂O₃ glasses are promising materials for optical functional applications.     

Effects of dissolved carbonate on arsenate adsorption and surface speciation at the hematite--water interface

Effects of dissolved carbonate on arsenate [As(V)] reactivity and surface speciation at the hematite-water interface were studied as a function of pH and two different partial pressures of carbon dioxide gas [P(CO2) = 10(-3.5) atm and approximately 0; CO2-free argon (Ar)] using adsorption kinetics, pseudo-equilibrium adsorption/titration experiments, extended X-ray absorption fine structure spectroscopic (EXAFS) analyses, and surface complexation modeling. Different adsorbed carbonate concentrations, due to the two different atmospheric systems, resulted in an enhanced and/or suppressed extent of As(V) adsorption. As(V) adsorption kinetics [4 g L(-1), [As(V)]0 = 1.5 mM and I = 0.01 M NaCl] showed carbonate-enhanced As(V) uptake in the air-equilibrated systems at pH 4 and 6 and at pH 8 after 3 h of reaction. Suppressed As(V) adsorption was observed in the air-equilibrated system in the early stages of the reaction at pH 8. In the pseudo-equilibrium adsorption experiments [1 g L(-1), [As(V)]0 = 0.5 mM and I = 0.01 M NaCI], in which each pH value was held constant by a pH-stat apparatus, effects of dissolved carbonate on As(V) uptake were almost negligible at equilibrium, but titrant (0.1 M HCl) consumption was greater in the air-equilibrated systems (P(CO2) = 10(-3.5) atm) than in the CO2-free argon system at pH 4-7.75. The EXAFS analyses indicated that As(V) tetrahedral molecules were coordinated on iron octahedral via bidentate mononuclear ( 2.8 A) and bidentate binuclear (approximately equal to 3.3 A) bonding at pH 4.5-8 and loading levels of 0.46-3.10 microM m(-2). Using the results of the pseudo-equilibrium adsorption data and the XAS analyses, the pH-dependent As(V) adsorption under the P(CO2) = 10(-3.5) atm and the CO2-free argon system was modeled using surface complexation modeling, and the results are consistent with the formation of nonprotonated bidentate surface species at the hematite surfaces. The results also suggest that the acid titrant consumption was strongly affected by changes to electrical double-layer potentials caused by the adsorption of carbonate in the air-equilibrated system. Overall results suggest that the effects of dissolved carbonate on As(V) adsorption were influenced by the reaction conditions [e.g., available surface sites, initial As(V) concentrations, and reaction times]. Quantifying the effects of adsorbed carbonate may be important in predicting As(V) transport processes in groundwater, where iron oxide-coated aquifer materials are exposed to seasonally fluctuating partial pressures of CO2(g).     

Increasing Efficiency of Force-Controlled Robotic Assembly: -Design of Damping Control Parameters Considering Cycle Time-

Parameter tuning of force control to achieve operations efficiently in robotic assembly is essential but time-consuming. In this paper, an optimal set of parameters for damping control is computed, which can reduce the cycle time of an assembly operation. The proposed method is formulated as a nonlinear optimization using a dynamic simulator based on 3D geometric model of assembled parts. The method is applied to clutch assembly for practical use. The results verify how the operations can be sped up using the obtained parameters. The proposed method enables users to introduce force control agilely.     

Characteristics on PWM CSI-induction motor drive system with utility interactive photovoltaic generation

This paper proposes a PWM current source inverter-induction motor drive system with photovoltaic generation. Solar cells are inserted in dc link to obtain constant current characteristics. They are connected to the utility system with a PWM converter. The PWM converter is controlled to obtain the maximum output photovoltaic (PV) power. The PWM inverter supplies sinusoidal currents for an induction motor, which is driven by constant V/f control. A pulsewidth control is utilized in the inverter section because of constant dc link current caused by peculiar V-I solar cell characteristics. In the system proposed here, the PV power is not only used for inverter-induction motor drive but it also flows into the utility system. The experimental results in steady state show that the proposed system has sinusoidal current with unity power factor in the utility system, the maximum output PV power and sinusoidal current/voltage for a motor. The demonstrated results for the separation of the utility system or the motor from the converter-PV-inverter system are given. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 79–87, 1997