Fluidization in dry landslides

This paper aims at determining the physical properties affecting the distance travelled by landslides with dry particles, and elucidating the mechanism of the properties affecting landslide fluidization. The procedure is as follows: laboratory landslide experiments were conducted to verify the simulation model which was proposed to represent the movement of landslides. Further, sensitivity analysis for some physical properties affecting the travel distance were conducted using this model. The simulation model could identify the coordinates, velocity and angular velocity for every particle in three-dimensional space, and the kinetic energy of particles consumed by inelastic and frictional collision with each other in the model. The travel distances of landslides simulated by the model were verified by laboratory experiments statistically where the physical properties for the particles and slope angle were changed. Then, sensitivity analysis for the physical properties were conducted using the model to clarify the effect of the properties on the travel distance. It was proven that there were no significant differences between the travel distances represented by the simulation model and those found experimentally using statistical analysis (i.e. the simulation model could represent virtual real landslides). From the sensitivity analysis using the simulation model, the travel distances were positively correlated to volume, or number of particles, and negative correlated to the slope angle, kinetic friction and rolling friction of particles when the initial potential energies were the same. The mass of particles of equal size did not affect the distance travelled. As the number of particles increased, the simulated travel distances tended to be longer compared with theoretical travel distances calculated using the friction between particles and the slope. Consequently, we could determine the distance of the lumped mass model as being critical between fluidized and non-fluidized landslides.     

Using GIS to develop a mobile communications network for disaster-damaged areas

Communications network damage resulting from a large disaster causes difficulties in the ability to rapidly understand the current situation and thus make appropriate decisions towards mitigating problems, such as where to send and dispense emergency supplies. The research outlined in this paper focuses on the rapid construction of a network after a disaster occurs. This study suggests ZigBee and geographic information systems (GIS) technologies to resolve these problems and provide an effective communication system. The experimental results of the ZigBee network system are presented, examples are provided of the mapping and analysis undertaken using GIS for the disaster-stricken area of Tsukuba City, Japan, and the communications node arrangements are determined for this region. These results demonstrate the effectiveness of establishing such a communications system for supporting efforts to relieve disaster-damaged areas.