A dot pattern of a refractive-index change was formed by spot heating with laser-beam irradiation on sodium tellurite glasses. The 15Na₂O · 85TeO₂ (mol. %) glass doped with 2 mol. % of CoO was irradiated by a green light-beam spot (532 nm) ∼800 μm in diameter from the second-harmonic generator of a Q-switched pulsed YAG laser. The map of the refractive index of the glass was determined with an He–Ne laser beam by a scanning ellipsometric technique at a resolution of 100 μm × 50 μm, indicating that the spots possessing a refractive index lower by ∼0.05 were formed at the region irradiated by the laser beam.

Nowadays, in the after-treatment of diesel exhaust gas, a diesel particulate filter (DPF) has been used to trap nano-particles of the diesel soot. However, as there are more particles inside the filter, the pressure which corresponds to the filter backpressure increases, which worsens the fuel consumption rate, together with the abatement of the available torque. Thus, a filter with lower backpressure would be needed. To achieve this, it is necessary to utilize the information on the phenomena including both the soot transport and its removal inside the DPF, and optimize the filter substrate structure. In this paper, to obtain useful information for optimization of the filter structure, we tested seven filters with different porosities and pore sizes. The porosity and pore size were changed systematically. To consider the soot filtration, the particle-laden flow was simulated by a lattice Boltzmann method (LBM). Then, the flow field and the pressure change were discussed during the filtration process.

When a fire breaks out in a tunnel, smoke diffuses widely in the direction of the ventilation airflow. As a result, the evacuation environment may not be sufficiently safe during a fire incident. When ventilation equipment in a tunnel is changed, the safety and economic efficiency of the new ventilation equipment must be evaluated in advance. However, it is dangerous and not financially feasible to undertake the verification of new ventilation equipment by performing a demonstration experiment owing to its cost and versatility. It is therefore useful for predicting an evacuation situation in which a fire breaks out in a tunnel by performing a numerical simulation and examining the evacuation safety of the tunnel. In this study, a tunnel fire was reproduced using the Fire Dynamics Simulator (FDS) fire simulation software. Moreover, an evacuation was simulated using the real-coded cellular automaton (RCA) method and the effects of the wind velocity and the number of evacuees in the tunnel on the evacuation time were examined.

To reduce particulate matter (PM) including soot in diesel exhaust gas, a diesel particulate filter (DPF) has been developed. Since it is difficult to observe the phenomena in a DPF experimentally, we have conducted a lattice Boltzmann simulation. In this study, we simulated the flow in a metallic filter. An X-ray computed tomography (CT) technique was applied to obtain its inner structure. The processes of soot deposition and oxidation were included for a continuously regenerating diesel filter. By comparing experimental data, a parameter of soot deposition probability in the numerical model was determined.