Seismic Earth Pressure Exerted on Retaining Walls Under a Large Seismic Load

In recent years, serious damage has been done to retaining structures because of large earthquakes. In order to establish practical methods for evaluating the seismic earth pressure, which is one of the important external forces acting on retaining structures during large earthquakes, a series of shaking table tests was conducted on retaining wall (RW) models. The experiments revealed that the seismic active earth pressure was considerably smaller than that obtained by the Mononobe-Okabe theory, particularly under a large seismic load. Furthermore, it was demonstrated that the seismic earth pressure had an upper limit, which was determined by the force equilibrium of the soil wedge at the critical state when the RW lost its stability. On the basis of the test results, a new method to evaluate the seismic earth pressure for practical designs under a large seismic load has been suggested. This proposed method provides a reasonable earth pressure as well as an angle of failure plane, those of which depend on the seismic stability of the retaining wall. It has been confirmed that earth pressure obtained by the proposed method agrees well with the measured seismic earth pressure exerted on several retaining walls with different degrees of stability.     

Stabilization of β-Bi2O3 by Sb2O3 Doping

The metastable β form of bismuth sesquioxide was obtained by doping antimony oxide. The solubility of antimony was 4 to 10 at. %in β specimens, where more than 75% of the antimony atoms were valenced at 5+.     

Motion of 2D Buoyant Clouds Downslope

The motion of conservative 2D thermals on beds with slope angles θ ranging from 5 to 90° is investigated theoretically and experimentally. Using a large number of experimental data, important flow characteristics, including the shape factors, spatial growth rate, propagation speed, and entrainment coefficient, are quantified as functions of bottom slope angles. A thermal model, which includes a resistance term, is developed. It is found semiempirically that resistance coefficients Cd are almost independent of θ and the values of Cd are in the range of 0.4–0.6. Capability of the model is demonstrated by comparing numerical results with theoretical as well as experimental results.     

A comparison of the hydrolysis of sweet potato starch with β-amylase and infrared radiation allows prediction of reducing sugar production

The apparent reaction rate constants (k) of the reaction that generates reducing sugar (presented as mg maltose equivalents) from raw sweet potato starch by using β‐amylase were determined by varying enzyme concentration, starch concentration and pH. The Arrhenius plot of the k‐value reached a peak at approximately 86 °C; the activation energy and frequency factor were also determined. Moreover, the amount of reducing sugar produced in sweet potato heated by infrared irradiation was estimated by using the values of k and the kinetic parameters. The calculated amounts of reducing sugar produced generally agreed with the experimental values. These results indicate that the amount of reducing sugar produced in heat‐treated sweet potato can be predicted by the methodology described in this study.     

Effects of High Irradiance and Low Water Temperature on Photoinhibition and Repair of Photosystems in Marimo (Aegagropila linnaei) in Lake Akan,Japan

The green alga Aegagropila linnaei often forms spherical aggregates called “marimo” in Lake Akan in Japan. In winter, marimo are exposed to low water temperatures at 1–4 °C but protected from strong sunlight by ice coverage, which may disappear due to global warming. In this study, photoinhibition in marimo was examined at 2 °C using chlorophyll fluorescence and 830 nm absorption. Filamentous cells of A. linnaei dissected from marimo were exposed to strong light at 2 °C. Photosystem II (PSII) was markedly photoinhibited, while photosystem I was unaffected. When the cells with PSII damaged by the 4 h treatment were subsequently illuminated with moderate repair light at 2 °C, the maximal efficiency of PSII was recovered to the level before photoinhibition. However, after the longer photoinhibitory treatments, PSII efficiency did not recover by the repair light. When the cells were exposed to simulated diurnal light for 12 h per day, which was more ecological, the cells died within a few days. Our results showed new findings of the PSII repair at 2 °C and serious damage at the cellular level from prolonged high-light treatments. Further, we provided a clue to what may happen to marimo in Lake Akan in the near future.     

A practical design of multiloop robust PID control systems

In this paper, a new design scheme of multiloop predictive self‐tuning PID controllers is proposed for multivariable systems. The proposed scheme first uses a static precompensator as an approximately decoupling device in order to roughly reduce the interaction terms of the controlled object. The static matrix precompensator is adjusted by an on‐line estimator. Furthermore, by regarding the approximately decoupled system as a series of single‐input single‐output subsystems, a single‐input single‐output PID controller is designed for each subsystem. The PID parameters are calculated on‐line based on the relationship between the PID control and the generalized predictive control laws. The proposed scheme is numerically evaluated on a simulation example. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(3): 63–71, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10284     

Crazing mechanism based on plastic instability

The mechanism of the nucleation of craze from the region of pre-formed voids is discussed on the basis of the finite elements analysis for an elastic plastic material containing a twodimensional array of cylindrical voids. Calculations are made for the two kinds of boundary conditions with respect to the constraint of the transverse strain under simple tension. The craze formation is considered to be an unstable concentration of plastic strain within the ligament between neighbouring voids. The present calculation shows that the constraint of the transverse strain is the essential factor in craze formation.     

Effects of viscosities on the transient current in homeotropic nematic liquid crystal cells

Effects of the Leslie viscosity coefficients α_i (i = 1, 2, …, 5) of nematic liquid crystals (NLCs) with negative dielectric anisotropy (Δε < 0) on the electric-field-induced director reorientation in homeotropic NLC cells have been studied from the analysis of the transient current induced by step voltage application. The transient current in a homeotropic NLC cell with Δε < 0 was well reproduced by computer simulation, based on the theory of NLCs in which the flow effects and the free-slip boundary condition are taken into account. It is found that the response time of vertical alignment NLC displays is dominantly governed by α₂ and α₄ + α₅ of NLCs with Δε < 0.