Text data with spatio-temporal information are becoming common with the popularization of mobile phones with a GPS function and microblog services like Twitter. This study proposes a system ...supporting operators in a disaster prevention center who control an area in real-world. Our system has three functions: (i) automatic classification that classifies messages into a fixed category, (ii) clustering that aggregates similar messages and (iii) burst detection that detects an event in which messages are arising in high frequency. We asked 120 people to send text data with spatio-temporal information by cell phones in the Osaka Expo Memorial Park. We evaluated our system using the above data.
We assessed a quartz pressure sensor characteristics assuming an ocean bottom and borehole environment in the laboratory. Accuracy evaluations of the hydraulic pressure sensors with a scale of 1 hPa ...are required for obtaining small pressure change related to crustal deformations on the seafloor. However, quantitative assessments to understand pressure sensor characteristics are not performed yet. We performed 4 patterns of experiments to understand characteristics. A pressure hysteresis width was 3.21 and 1.56 hPa for the applied pressure width of 10 to 30 MPa and 15 to 25 MPa, respectively. The temperature characteristics of the sensor are 3.12 hPa/degC. The temperature hysteresis of the sensor is 1.12 hPa when the outside environment of the pressure sensor is 3.0 degC. The tilt characteristics of the pressure sensor is 0.42 hPa/degC. These characteristics of the quartz pressure sensor would influence on detection of small amount of crustal deformation on the seafloor.
Vehicles are used to transport people and goods efficiently. In order to move smoothly, even in an environment with limited space or numerous obstacles, the vehicle that can not only move in the ...longitudinal direction and turn but also move in the lateral direction is required. In order to satisfy this requirement, wheel mechanisms for lateral movement, such as the active omni wheel (AOW), which is a wheel that is movable in an arbitrary direction actively, have been proposed. However, these wheel mechanisms require numerous motors to construct a vehicle, which leads to increased size, weight, and manufacturing cost of the vehicle. In order to address this problem, the present study proposes a drive mechanism for driving AOWs by a small number of motors using switchable clutches. Vehicles equipped with this drive mechanism can move in the longitudinal and lateral directions and turn by just one or two motors. In the present paper, the structure and motion of the proposed drive mechanism are explained. Through the kinematic analysis, the establishment condition is derived. Based on the results, several structures of vehicles equipped with the proposed mechanism are introduced. Experiments are conducted using the developed vehicle, and the effectiveness of the proposed mechanism is verified.
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