ALBERT

Description: With robots becoming closer to humans in recent years, human-friendly robots made of soft materials provide a new line of research interests. We designed and developed a soft robot that can move via self-deformation toward the practical application of monitoring children and the elderly on a daily basis. The robot’s structure was built out of flexible frames, which are bending-type pneumatic artificial muscles (BPAMs). We first provide a description and discussion on the nature of BPAM, followed by static characteristics experiment. Although the BPAM theoretical model shares a similar tendency with the experimental results, the actual BPAMs moved along the depth direction. We then proposed and demonstrated an effective locomotion method for the robot and calculated its locomotion speed by measuring its drive time and movement distance. Our results confirmed the reasonability of the robot’s speed for monitoring children and the elderly. Nevertheless, during the demonstration, some BPAMs were bent sharply by other activated BPAMs as the robot was driving, leaving a little damage on these BPAMs. This will be addressed in our future work.

Description: The central Hokkaido, Northern Japan, was struck by an earthquake of M6.7 on September 6, 2018. Its deep hypocenter of 37 km might result of a complex crust and upper mantle structure in Hidaka arc-arc collision system. A seismic intensity of 7 on the Japan Meteorological Agency (JMA) scale was observed at Atsuma Town. About 90% of the casualties were due to the multiple earthquake-induced landslides in Atsuma Town, and a significant number of houses in the urban areas of Sapporo were damaged due to soil liquefaction. Destruction of electric power facilities near the epicenter caused a long-term power outage in approximately 2,950,000 houses in Hokkaido. The widespread blackout caused secondary damages to utilities, civil life, and economic activities in the region. The number of refugees from this incident was approximately 13,111 in maximum, and the economic damage also increased further as a result of the electric blackout. The Hokkaido Prefectural Government immediately applied the Disaster Relief Act on that accrual day. On September 28, 2018, the National Government certified the event as the Designated Disaster of Extreme Severity.

Description: The earthquake (Mw 7.3) that struck Nepal on April 25, 2015 caused damage to many civil engineering and architectural structures. While several road gabion retaining walls in mountainous regions incurred damage, there was very little information that could be used to draw up earthquake countermeasures in Nepal, because there have been few construction cases or case studies of gabion structures, nor have there been experimental or analytical studies on their earthquake resistance. Therefore, we conducted a shake table test using a full-scale gabion retaining wall to evaluate earthquake resistance. From the experiments, it was found that although gabion retaining walls display a flexible structure and deform easily due to the soil pressure of the backfill, they are resilient structures that tend to resist collapse. Yet, because retaining walls are assumed to be rigid bodies in the conventional stability computations used to design them, the characteristics of gabions as flexible structures are not taken advantage of. In this study, we propose an approach to designing gabion retaining walls by comparing the active collapse surface estimated by the trial wedge method, and the experiment results obtained from a full-scale model of a vertically-stacked wall, which is a structure employed in Nepal that is vulnerable to earthquake damage. When the base of the estimated slip line was raised for the trial wedge method, its height was found to be in rough agreement with the depth at which the gabion retaining wall deformed drastically in the experiment. Thus, we were able to demonstrate the development of a method for evaluating the seismic stability of gabion retaining walls that takes into consideration their flexibility by adjusting the base of the trial soil wedge.

Description: This study aims to clarify the relation between preparedness status and the local natural resource conservation of small and medium-sized enterprises (SMEs). SMEs are key actors in sustainable development and local disaster risk reduction. To ensure the quick recovery of business, SMEs are expected to formulate a Business Continuity Plan (BCP). However, the rate of formulation has thus far not been very high among SMEs. This study conducted a questionnaire survey in 2017 targeting SMEs in Sukagawa, Fukushima. We analyzed the 240 responses collected through a Multiple Correspondence Analysis and used Cramer’s coefficient of association to determine the strength of association. Major findings are as follows: 1) Environment-related indices were associated with both BCP formulation and business size, and these associations indicate the possibility of connecting environmental actions or management to BCP formulation. 2) In the association between BCP formulation status and environmental actions, the environmental management system had a stronger association than business size (capital, number of employees). 3) The group interested in the conservation of regulating services related to local natural resources (reducing CO2 emission, water quality, aquatic plants and animals) had a higher rate of BCP formulation. 4) This group considers mutual help more important than self-help or public help. 5) Capital and number of employees have a strong association with both BCP formulation status and their interest in participating in local natural resource conservation. Activities with local society and stakeholders may collectively increase SMEs’ awareness with neighbor enterprises or the local community. It would help both SMEs and local society to build a seamless attitude toward disaster risk reduction, which would contribute to local sustainability.

Description: Image reconstruction in computed tomography can be treated as an inverse problem, namely, obtaining pixel values of a tomographic image from measured projections. However, a seriously degraded image with artifacts is produced when a certain part of the projections is inaccurate or missing. A novel method for simultaneously obtaining a reconstructed image and an estimated projection by solving an initial-value problem of differential equations is proposed. A system of differential equations is constructed on the basis of optimizing a cost function of unknown variables for an image and a projection. Three systems described by nonlinear differential equations are constructed, and the stability of a set of equilibria corresponding to an optimized solution for each system is proved by using the Lyapunov stability theorem. To validate the theoretical result given by the proposed method, metal artifact reduction was numerically performed.