The committee for reusing of aggregates extracted from waste concrete was inaugulated in 1977. Although some gidances to the permissible qualities for concrete use were presented by the committee, some roads constructed by the recycled aggregates become to cave or to crack on the pavement or the roadbed. One of the causes has to decide that it could not entirely remove the mortar on the original stone. It is expected to develop the effective elimination technique of the mortar removing.

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Utilization of digital topographic data for open pit mines was analyzed, including topographic map generation, modification of maps and estimation of mine productivity. On previous topographic maps of open-pit mines generated by computer systems, construction details, such as working faces and roads, were difficult to identify from the contour lines. In these maps, many contour lines were drawn very close together due to large fluctuations in topographic features. The presence of large numbers of contour lines often obstructed construction details. To identify these construction details, the outlines of each construction were drawn, and the contour lines enclosed by these outlines were erased. Furthermore, construction details, such as manufacturing plants and office buildings, which were not identified by the contour lines, were drawn using the same algorithm. Highly detailed maps that distinguished these construction details from contour lines were then created. This digital topographic data was useful for simulating scene changes and the extent of mining. Computer graphics allowed simulation of scene changes in advance, and provided basic data concerning future changes. Moreover, these maps allowed accurate estimates of mine production to be calculated. To generate these maps, GPS (Global Positioning System) was utilized to measure topographic changes only where the operations had taken place. Furthermore, construction detail outlines were also obtained from the operator's input previously arranged by the rule, i.e. inputting a set of surveyed points for construction. This mapping system easily maintained monthly or annually updated data on topographic and construction changes. For production schedule simulation, topographic maps, computer graphics, and product estimations based on monthly or annually up-to-date digital topographic data were useful.

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In the previous papers, control performance of servo-controlled testing machines with a symmetrical cylinder was discussed analytically and numerically. An asymmetrical cylinder is widely used to reduce the cost and size of testing machines. However the asymmetrical cylinder has nonlinear characteristics, and the control performance of it is inferior to the symmetrical cylinder. In this paper, the control performance of a servo-controlled testing machine with asymmetrical cylinder is discussed analytically on basis of the experimental results. Uniaxial compression tests using Sanjome-andesite, Akiyoshi-marble and Inada-granite were conducted in order to clarify the control characteristics. Actually, pressures of upper and lower chambers within the cylinder were measured. It was found that the pressures changed depending on the direction of piston movement. The pressure decreased in case of moving to the loading direction, and the amount of pressure decrease was large at high piston velocity. The pressures in the cylinder were analytically examined with aid of a simple model which consisted of a cylinder and a servo-valve. These theoretical results coincided with the experimental results. Sometimes in the post-failure region, the piston tended to move reversely. At that time, the asymmetrical cylinder showed inferior control performance caused by the followings ; 1) Larger amount of oil inflow is necessary. 2) Feedback gain changes depending on the direction of piston movement. The control performance of asymmetrical cylinder can be possibly improved by adjusting the followings; 1) large oil-leakage at the cylinder, 2) variable flow-coefficient at orifice, 3) variable feedback gain.

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The investigations on artificial aggregate from coal fly ash have been continued long time, and a few productions are realized. Mass production of aggregate that has stable quality has been uneasy, because the electric power plants in Japan use many kinds of coal, and chemical compositions and unburned coal contents of the fly ashes are not uniform. Low water absorption and high strength are indispensable for aggregate for concrete. In view point of production, stability in quality is desirable against firing temperature change. In order to produce an aggregate of stable quality from different fly ash, authors have studied on properties of the fly ashes, pellets fired in rotary kiln and the concrete using fired pellet (aggregate). Some relations between physico-chemical properties of 24 fly ashes and its fired behaviors are reported herein. As a result, fly ashes were divided into two groups： one reached highest density at the temperature less than 1,200°C (low temperature group), the other at higher than 1,250°C (high temperature group), reflecting their chemical and mineralogical compositions. The former is mainly sintered by the presence of univalent K as a flux and the latter is sintered by divalent Ca, Mg adding to K. Plagioclase consisted in the former and cristobalite in the latter as a prominent mineral of sintered body. Hemisphericalizing temperature correlated to mullite content, and degree of densification corresponded to glass content. Compressive strength roughly depended on specific gravity of sintered body.

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"Magnetic solid flocculant" (MSF) is a new type flocculant with high magnetic intensity and high positive charge which is useful for the flocculation of fine particles in suspension. The MSF prepared by adsorbing cationic polyelectrolytes to the surface of magnetite particles have abilities to capture fine particles by electrostatic force in a wide pH range and to recover the flocs quickly by magnetic force without changing liquid property. In this study, four kinds of cationic polyelectrolytes are used in preparing MSF and the optimum condition of MSF production is investigated. For all cases, higher pH (especially above pH 7) during polyelectrolytes adsorption gives MSF higher surface potential, and higher polyelectrolyte concentration gives better MSF dispersion. It is observed that three kinds of polyelectrolytes above 300,000 of molecular weight do not detach from a magnetite surface even after several washings. This result indicates that the MSF keeps stable high surface potential and, therefore, can be used repeatedly. Among the four kinds polyelectrolytes used in this study, polyethyleneimine type (molecular weight: 300,000) is the best for MSF production. The optimum condition is as follows; polyelectrolytes concentration: 1,000 ppm, adsorption pH: pH 8, washing after adsorption: 3 times. The MSF produced under optimum condition has large positive potential of around 40 mV in 10-3mol/l NaCl solution in a wide pH range.

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SrAl2O4 : Eu2+, Dy3+ as a light-storage phosphor was prepared by a solid state reaction. Oxide fluxes were added in SrAl2O4 : Eu2+, Dy3+ in order to control the particle size and shape. The effects of sintering conditions and Eu2O3, Dy2O3 and flux contents on the phosphorescent property of SrAl2O4 : Eu2+, Dy3+ were discussed. The optimum synthesis conditions were discussed in terms of the initial intensity of phosphorescence of SrAl2O4 : Eu2+, Dy3+ because the attenuation constant in each sample did not change. As a result, the optimum conditions to fabricate SrAl2O4 : Eu2+, Dy3+ were 1,773 K, 3 h, 2 %-H2/ 98 %-Ar atmosphere, 0.4 mol% Eu2O3, 0.4 mol% Dy2O3, and 3 mol% B2O3 as a flux.

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The removal of carbon impurity from Nd2S3 has been studied by heating in the gases of 4 % H2/N2, H2S and NH3. When the sulfide containing 1,200 mass ppm carbon impurity was heated in 4 % H2/N2 or H2S at 1,600 °C for 1 h, the carbon content decreased to 600 mass ppm. With NH3 gas, the carbon content decreased to 850 mass ppm by heating at a lower temperature of 1,000 °C for 1 h. Prolonged heating for 5 h resulted in further decrease of carbon content to 600 ppm. The mechanism of reaction of carbon with the above different gases is discussed in relation to the free energy change associated with the reactions. The phase transformation from - to -Nd2S3 was observed after the decarbonization with 4 % H2/N2 and H2S, while it did not occur during the low temperature processing at 1,000 °C in NH3.

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A comprehensive mathematical model was developed to simulate the reduction of ilmenite ore with carbon in commercial electric furnaces. Two distinct reaction sites were assumed to exist in an open arc furnace : seething surface and bulk bath of titania slag. The model takes into account such physical features as surface tension (or Laplace-Kelvin pressure), viscosity and density (or residence time by Allen's law), together with equilibrium mass balances incorporating the thermodynamic properties of the TiO2 - TiO1.5 - TiO - FeO - SiO2 - AlO1.5 - MgO slag and the molten Fe-C metal. The model explains all known industrial observations : interdependence of the TiO2 content of slag and the carbon content of pig iron, its variation with temperature, electric power consumptions, and so forth. The model also provides partial explanations for the foaming and permanent CO gas boiling of the slag. The computer model predictions can be used to monitor and optimize the conditions for smelting different ores in various operating modes.

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The γ-, δ-, λ-, κ-, η-, θ- and α-aluminas were prepared by heating the crystalline aluminium hydroxides at selected temperatures. The vibrational spectra of those aluminas were determined in the far-infrared (FIR) region. In order to assign the low-frequency vibrations of aluminas, the characteristic frequencies of octahedral AlO6 and tetrahedral AlO4 groups were determined by using both the crystal structures of θ- and α- aluminas.

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