Steel fiber reinforced shotcrete or concrete (SFRC) is used for supporting of slope and tunnel when condition is severe. Steel fibers in shotcrete is considered to improve crack
In this study, uniaxial tensile tests of SFRC was conducted by servo-controlled testing machine to obtain complete stress-strain curves. In the experiment, volume fraction of steel fiber in shotcrete was chosen to be 0, 0.5, 1.0, 1.5 %. Considering anisotropy of SFRC, two kinds of cylindrical specimens were made boring parallel and normal to bedding plane.
The experimental results in uniaxial tension can be summarized;
1) The strength and residual strength indicate anisotropy of SFRC. Both are larger when stress is applied parallel to bedding plane.
2) The strength and Young's modulus were not affected with volume fraction of steel fiber (Vf [%]), however the residual strength (σRE [MPa]) increases following the equation, σ_RE=5×10^-6×(12.5-Y) ⁵×Vf where Y [mm] is displacement.
3) In residual strength region beyond peak strength, steel fibers are gradually pulled out from shotcrete. The residual strength is caused by pulled out resistance of steel fibers.
4) The number of steel fiber appeared on the fractured surface is smaller than that on cutting surface. Fractured surface tends to develop on the weakest plane where relatively a small number of fibers cross the plane.

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In order to analyze the lateral vibration of an offshore structure supported by the seabed layer, its effect on the vibration should be taken into consideration. The lateral deflection of an elastic vertical pipe, which was partially supported by the seabed layer and at the top of which a concentrated lateral force was applied, was theoretically analyzed by assuming the uniform and exponential distributions for the stiffness of the layer. Then, experiments were carried out on the force-deflection relationship of an elastic pipe under the same condition as mentioned above. In addition, the values of the stiffness for the various thickness of the sand layers under various conditions were determined by comparing the theoretical deflections with the experimental ones.
Furthermore, the free lateral vibration of the above-mentioned pipe considered as a leg of an offshore structure was theoretically analyzed by using the above-obtained static stiffness of the sand layer. The result indicated that both the theoretical natural frequencies pertaining to the uniform and exponential distributions of the stiffness of sand layer fairly well coincided with the experimental frequency, and the latter distribution of stiffness gave a little better estimation than the former. Moreover, the nondimensional quantity CSD defined in this study among the natural frequency of lateral vibration of the pipe, the stiffness and linear damping coefficients of sand layer was found to be nearly constant in various cases of the sand layers without above water-layer, such as CASE 1 and CASE 2. Thus, the damping coefficients in these cases could be easily obtained by this CSD if the natural frequency of lateral vibration of the pipe and the stiffness of the sand layer were known in advance.
Finally, in order to evaluate the damping coefficient of the sand layer, above which the water-layer exists, in CASE 3, corresponding to the practical case, the coefficient was calculated by multiplying the damping coefficient for CASE 2 of wetted sand layer without above water-layer by the frequency-ratio of CASE 3 to CASE 2, under the assumption that the damping coefficient was proportional to the natural frequency of lateral vibration of the pipe if the thickness of sand layer were constant. The obtained damping coefficient for CASE 3 fairly well coincided with the experimental one, identifying the validity of the above-mentioned assumption and procedure. Hence, this procedure could be applicable for finding the damping coefficient of seabed layer in practical cases.

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This paper treats theoretical analyses to predict the steady flow characteristics of multiphase mixture in an air lifting pipe. When slurries containing solid particles such as manganese nodules are lifted from the deep-sea bed to the sea surface by an air lift pump, gas phase is injected halfway into a lifting pipe with a very large length ranging from the sea floor of about 5, 000 m in depth to the sea surface. Therefore, liquid-solid two-phase flow is formed in a deeper part of the lifting pipe, but changes into gasliquid-solid three-phase flow just after the position of the gas injection.
Here, the case is treated where slurries are the solid particles-sea water two-phase mixture before the position of the gas injection and the air-solid particles-sea water three-phase mixture after that. The equations governing the liquid-solid two-phase slurry flow consist of two continuity equations, two momentum equations and an equation for two-phase volume fractions. However, the gas-liquid-solid threephase flow field after the position of the gas injection is governed by three continuity equations, three momentum equations, a gas equation of state and an equation for three-phase volume fractions. In the two-phase region, the individual volume fractions and lifting velocities of the solid and liquid phases remain self-evidently unchangeable. The abrupt drop of the volume fractions as well as the abrupt jump of the lifting velocities occur at the transitional position from the two-phase to the three-phase flow. In the three-phase region, the three momentum equations for the individual phases are solved as the perturbation from the solutions to the equilibrium/homogeneous flow and then the remaining five flow properties are determined.
Some numerical experiments are performed using a set of five equations in the two-phase region and a set of eight equations in the three-phase region for determining the flow properties. By comparing the non-equilibrium solutions with the numerical results of the case where the three-phase flow is assumed to be in velocity equilibrium, it is numerically shown that the equilibrium solution gives a threshold of the highest possible solid-phase mass flux on condition that bath the gas-phase and liquid-phase mass fluxes are kept constant. With increasing solid particle size the non-equilibrium solution obtained directly as the perturbation from the equilibrium one is found to have a tendency to deviate from the original equilibrium one. Such important problems are described in detail.

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We report the mathematical basis of a recent enhancement incorporated within an algorithm entitled “Switching mode Enhanced Extended Kalman” (SEEK) filter algorithm. The SEEK filter algorithm was inspired by the motive of enhancing the convergence rate of the estimation error covariance matrix by optimally selecting the observation matrix. As a measure of the convergence rate we focus attention on the trace of the Jacobian matrix for the Riccati-type matrix differential equation consisting of the current state transition matrix, the driving matrix, the observation matrix and the observation noise covariance matrix. In the SEEK filter algorithm the observation matrix is switched so as to ensure the objective function is maximised. As a demonstration here, we offer the dual-states Lorenz system with superimposed Gaussian white noise, and the discrete vortex models characterising three vortices behaviour are also identified. We confirm a singular improvement achieved by the SEEK algorithm over the conventional extended Kalman filter.

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The authors have studied applicability of the H∞ control to bilinear plants, which can be encountered in different control plants of resources processing. Those plants are characterized by the model dynamics depending on the change of manipulated variable. The nominal transfer function was determined for the one concentration set point and the other concentration values except for the set point were regarded as factors inducing model deviations. Time variations of the manipulated variable and inverse responses of the controlled variables were also considered in the designing stage. The results shows that stable control can be achieved over a wide range of concentration value, i. e. controlled variable. The results were also compared with those from the fuzzy control applied to the process under the same conditions. The fuzzy control shows that the rise time is shorter than that in the H∞ control, but a big overshoot appeared when another rule table was used. It is considered that the H∞ control has a conservative tendency caused by establishing robust stability. However, it has an advantage of the systematic and routine design which can hardly be conducted in the fuzzy control.

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Removal of carbon from fly ash to a higher level has been attempted using flotation with kerosene oil as collector. Following pre-treatment was found to be effective in lowering the carbon content:(1) pH adjustment of pulp to the value around 7.(2) Emulsification of oil into aqueous phase before contacting with feed.(3) Modest pregrinding for liberation of organic component. It was also found that kerosene could be replaced by heavy oil A, cheaper and perhaps rather effective due to its surface-active impurities. However, addition of these collector oils required for flotation was still large; this problem should be solved by further improvement of above pretreatments. The purified material is now planned to be subjected to hydrothermal treatment for synthesis of alumino-silicate minerals as kaolinite.

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Bioreactor of iron oxidizing bacteria for industrial purposes, such as treatment of waste water drainage, are often a type of the recycle reactor, which is composed of three stages; oxidation, carrier settling and carrier recycling. It is difficult to understand the cell condition in the reactor, because the cells attach on the surface of carrier.
The purpose of this work is to characterize this bioreactor quantitatively from an analysis of phe-nomena caused by shifting temperature, during continuous operation for one year. The temperature dependence of bacteria yield, maximum specific growth rate and saturation constant were obtained from the result of batch experiment in the range of 15°C to 30°C. These parameter values were in the same range of the results reported by early researches. In the continuous operation during one year, the oxidation ability of the bioreactor was kept constant level. From a mathematical model, it was confirmed that cell number increased to supplement the decline of oxidation ability when it becomes low temperature.

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The leaching characteristics of manganese nodules were investigated in dilute hydrochloric acid solution by using copper matte as a reductant. The copper matte has been found to be an effective reductant for extracting more than 96 % of Mn, 95 % of Ni, 91 % of Co, 88 % of Cu, and 36 % of Fe when leached in 2.5 M HCl at 70°C for 2 h. The dissolution of Mn, Co and Ni depends on the amount of added copper matte. The ratio of liquid and solid is important factor on the extraction of metals during leaching. The dissolution of Mn, Co, Ni and Cu is increased with the increase in temperature of the leachant. The rate of Mn, Co, Ni and Cu leaching from manganese nodules in the presence of copper matte is limited by both the surface chemical reaction and pore diffusion processes. The activation energies for Mn, Co, Ni and Cu were 73, 53, 72 and 242 kJ/mol, respectively.

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The leaching characteristics of manganese nodules were investigated by using ammonium chloride solution with sodium sulfite as a reductant for leaching manganese, cobalt, nickel, copper and iron. Leaching behaviors of manganese, copper, cobalt and nickel depend on the amount of added sodium sulfite. The ratio of liquid and solid is an important factor in the extraction of metals during leaching. The dissolution of manganese, cobalt, nickel, copper and iron is increased with the increase in the NH₄Cl concentration and in the temperature of the leachant. When the leachant pH was kept constant, the leachability increased for each of the metals. The sodium sulfite has been found to be an effective reductant for extracting more than 95.8 % of Mn, 93.5 % of Ni, 98.5 % of Cu, 89.1 % of Co, 3.1 % of Fe when leached in 5 M NH₄Cl at 80 t for 2.5 h. The dissolution rates of Mn, Ni and Cu are controlled by pore diffusion, while Fe is controlled by surface chemical reactions and Co is limited by both the surface chemical reaction and pore diffusion process.

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The extraction of trivalent gallium, indium and thallium from aqueous solutions containing hydrochloric acid and/or lithium chloride by trioctyl phosphine oxide (TOPO) in benzene has been investigated under different conditions. The organic extracts are also examined by infrared spectroscopy. As the results, it is found that although the extraction efficiency for metals of TOPO is in the order Tl>Ga>In, these extractions are expressed as the following equilibrium equations: GaCl3 (aq) + TOPO (org) GaCl₃·TOPO (org); InCl₃ (aq) + 2TOPO (org)-IInCl₃·2TOPO (org); TlCl₃ (aq) + 2TOPO (org)-ITlCl₃·2TOPO (org) at low aqueous acidity, and TlCl₃ (aq) + HCl (aq) + 2TOPO (org)-I HTlCl₄-E2TOPO (org) at higher acidity. The extracted species consist of the complexes GaCl₃·2TOPO, InCl₃·2TOPO, Tl₂CL₆·₄TOPO and H₂Tl₂CL₈·₄TOPO. By applying the trial and error method of least-squares analysis to the equilibrium equations for these extraction systems, the stability constants of the aqueous chloro complexes of trivalent gallium, indium and thallium have been determined.

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