In the civil engineering construction field, it is often necessary to determine the ventilation requirements in order to maintain a minimum air quality for human breathing. This needs to take into account dilution of natural gushed gas and the exhaust gases from diesel equipment, the gases produced by the detonation of explosives and their dissipation time, as well as the dust generated by shotcreting. The purpose of such a ventilation plan is to specify the capacity and optimum location of the ventilation equipment, both of which are calculated simply.
Recent large-scale underground excavations such as power plant, energy storage, and so on, consist of complex lay-outs, deeply seated long openings, and substantial excavation volumes. Hence, they require rather sophisticated ventilation programs because of their huge pressure losses and air handling volumes.
The authors have applied coalmine ventilation technology to optimize the ventilation plan for such large-scale underground civil constructions. A quasi-three-dimensional ventilation network analysis method has been developed and applied to analyze the airflow in large scale geo-spaces.

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When the stresses are relieved by underground excavations, the rook mass tends to deforms perpendicular to the free surfaces and simultaneously macroscopical open cracks which is parallel to the surface are observed. In this case, the deformability of rock mass is largely dependent on the existence of open cracks, and the amount of crack opening is an important factor to the rock mass evaluation.
In this study, the Ratio of Crack Opening Dependency (RCOD) is proposed as a new index to evaluate the property of cracked structure which contains many open cracks within. The RCOD is an index which is defined as the ratio of total amount of crack opening and the total deformation of cracked structure. The mechanical property of RCOD is also numerically analyzed by applying SC-DDM (stress compensation-displacement discontinuity method) to 2-dimensional crack homogenization model. Here, the alternative model of a single crack set is assumed and the relation between RCOD and effective Young's modulus of the model is analyzed. The relation between RCOD and stress intensity factor is also discussed and the rationality of the analysis is confirmed. It is shown that RCOD is an useful index which directly indicate the effective Young's modulus and the stress intensity factor of cracked structure without any values such as stresses or crack size. The possibility of application of RCOD to the field measurements is also discussed.

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In Japan, the automobile production is increasing from year to year, proportionally to the economic growth. The increase in the number of newly automobiles put into circulation is followed by a larger amount of discarded automobiles. The huge amount of residues generating through this processing is usually dumped on land filling sites. The accumulation of these residues and the shortage of valuable disposal sites may cause some social and environmental problems (soil pollution). To deal with this nuisance, the authors have initiated and developed a processing system for shredded automobile residues on the basis that more than 90% of these residues are combustible materials that could be used as solid fuel: cotton and sponges (40.1%), plastics (30.2%) and rubbers (21.2%). The developed processing system is applied to residues in the range of -80+5 mm. Light materials, mainly cotton and sponges and light plastics in the shredded residues are recovered as float products from the ascending airflow passing through a vertical zig-zag air separator. Then moisture content of light materials is reduced to less than 15% at 450-550 °C. Afterward, they are processed into solid fuel through agglomeration. The calorie, ignition loss and weight percentage of chlorine are 5,000 kcal/kg, 36.0%, and 2.0%, respectively.

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Removal of heavy metal ions from the waste effluent is considered very important to maintain the environment free of any pollutants. We have developed a Pb-based compound that efficiently removed Selenium and Molybdenum from artificial wastewater. In this paper, we report the results of the study carried out to determine the applicability of this Pb-based adsorbent for the removal of Antimony. The following were concluded from the Sb ion adsorption study using Pb-based compound.
(1) The Pb-based compound showed the ability to adsorb Sb(III) ions from an artificial wastewater containing Sb ions. The maximum Sb(III) ion adsorption capacity of Pb-based compound was determined to be 0.94 kg·kg^-1 under the following experimental conditions: solution pH 4, Equilibrium concentration of Sb(III) ion of 35 mg·dm^-3, and agitation time, 2 hours.
(2) Based on XRD and SEM analysis of the Sb-ion adsorbed Pb-based compound, the presence of Pb(OH)Cl was identified. Furthermore, elements such as Sb, Fe, Cl and Pb were found evenly distributed on the surface. The Sb ion adsorption was pH dependent and for pH less than 8, more Sb(V) ions were adsorbed than Sb(III).
(3) Though the dissolution of Pb ions in the alkaline region was very low compared to the acid region, the concentration was above the wastewater permissible limit. Thus, the Pb ion concentration was brought below 0.1 mg·dm^-3 using zeolite.

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Woody biomass (Acacia Mangium) which contains 43 % (dry basis) of oxygen was converted by treatment in liquid water at temperature ranging from 270 to 350 °C, pressures 8.3 to 18.4 MPa, and holding time 10 minutes using an autoclave of 10 l capacity. At these reaction conditions a significant proportion of the oxygen was removed and the oxygen content of the solid product became 14-24 %. Oxygen removal increased the carbon content and the heating value, leading to a product with more sub-bituminous and bituminous coal-like properties. This solid product having heating values of 6,900-7,160 kcal / kg (dry basis) is an excellent fuel because of its higher volatile matter content, low sulfur and low ash. After cooling down the reaction mixture to ambient temperatures, the liquid product containing the organic components was dissolved in the process water. It is composed of mainly methyl alcohol, acetic acid, components derived from cellulose and hemi-cellulose such as 5-hydroxymethyl-2-furancarboxaldehyde and furfural, and lignin components such as 2, 6-dimethoxy-phenol and guaiacol. The mechanism of the conversion process is discussed through Fourier Transform Infrared Spectroscopy, Gas Chromatograph Mass Spectroscopy and Fluorescence Spectroscopy analysis results.

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In order to characterize the potassium-chabazite (K-CHA) obtained by hydrothermal synthesis with KOH from coal fly ash, various physical properties such as crystal structure, textures of surface and cross section of particles, cation exchange property, acid-resistance and heat-resistance were investigated for the synthesized K-CHA product.
The particle size of the K-CHA product has a maximum point at 20μ and a shape distribution. The particles of K-CHA consist of unreacted coal fly ash or coagulated fine particles of K-CHA as a nuclear. In case of pH over 4, the X-ray diffraction intensity of K-CHA decreases with a decrease in pH, but K-CHA crystals are not dissolved. On the other hand, K-CHA crystals are dissolved in the aqueous solution of pH below 4. In case of heat treatment below 873K, the X-ray diffraction intensity of K-CHA decreases with an increase in temperature, while the thermal decomposition of K-CHA and production of new crystalline materials do not take place. In the heat treatment of 1,273K, the peaks of K-CHA disappear in the XRD pattern and those of leucite newly generate. The K-CHA product contains about 10% of water and about 3% of unburned carbon.

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