Daifuku (Japan)

Abstract The threat of declining seaweed beds has been a concern around the world. Seagrass and seaweed (brown algae) beds are essential habitats supporting fisheries. However, approximately 22% of these habitats have been lost in Japan due to increased coastal landfill sites and ports. This study aims to rehabilitate the depletion of these habitats by constructing an artificial reef in Wakasa Bay, Japan, and monitoring Sargassaceae succession in the second and fourth years after the construction was completed. In this study, we set up four sites on the artificial reef. Then we identified the seaweed species composition and coverage of the Sargassaceae using underwater visual observation by scuba divers. The seaweed coverage was already over approximately 80% in the second year after construction. However, the dominant species changed to Sargassum horneri in the second year after construction and Myagropsis myagroides in the fourth year after construction. Thus, the recovery of species composition takes longer than that of coverage. Therefore, when the artificial reef is constructed, it is important to observe the recovery of species composition.

Abstract The threat of declining seaweed beds has been a concern around the world. Seagrass and seaweed (brown algae) beds are essential habitats supporting fisheries. However, approximately 22% of these habitats have been lost in Japan due to increased coastal landfill sites and ports. This study aims to rehabilitate the depletion of these habitats by constructing an artificial reef in Wakasa Bay, Japan, and monitoring brown algae (Sargassum and Myagropsis) succession in 2 years and 4 years after the construction was completed. In this study, we set up five sites on the artificial reef as a treatment area and one site on the natural reef as a control area and then identified the seaweed species composition of the Sargassum and Myagropsis communities and their coverage on each reef using underwater visual observation by scuba divers. The seaweed coverage on the artificial reef was already close to that on the natural reef in 2 years after construction. However, the dominant species on the artificial reef was not conformable to that on the natural reef in 2 years after construction. The dominant species on the artificial reef changed to S. horneri/S. confusum in 2 years after construction and M. myagroides in 4 years after construction. On the other hand, the dominant species on the natural reef changed to S. patens in 2 years after construction and M. myagroides in 4 years after construction. That is, the species composition on the artificial reef was close to that on the natural reef in 4 years after construction. Thus, the recovery of species composition takes longer than that of seaweed coverage on the artificial reef.

Indoor localization scheme using sensor networks is expected to be applied in various fields, and the localization scheme using time of arrival (TOA) is well-known. However, the estimation accuracy of TOA localization is severely deteriorated in non-line-of-sight (NLOS) environments, and the NLOS mitigation scheme such as iterative minimum residual (IMR) scheme is required. The IMR scheme is often applied because of its lower calculation complexity. However, when an increased number of NLOS nodes exist, the NLOS detection errors increase in the IMR scheme and the estimation accuracy deteriorates. Therefore, in this paper, we propose a new scheme exploiting rough NLOS detection based on stochastic characteristics before the application of IMR scheme to improve the localization accuracy. The improved performance is shown by computer simulations.

We consider an optimization of conflict-free routing problems for automated guided vehicles (AGV) with acceleration and deceleration. A continuous time model is developed to represent the dynamics of vehicles. In the proposed model, the transportation model is discretized into several regions. A network model is created by taking into account the acceleration and deceleration motions. The acceleration and deceleration are represented at curve locations. Column generation heuristic is used to find a near-optimal solution. In this algorithm, we construct a heuristic rule to generate a feasible solution with acceleration and deceleration of vehicles after the column generation. The pricing problem is represented by a resource constrained shortest path problem, which is effectively solved by a labeling algorithm. The dominance relation for acceleration and deceleration is addressed. In the proposed model, the dynamics of real speed AGV model are reflected into the routing problems. By comparing the performance of the conventional method, the effectiveness of the proposed method is demonstrated.

Collecting location information of persons or things in sensor networks enables a variety of services and applications. For such location information, time of arrival (TOA) or angle of arrival (AOA) of radio waves is often used. Moreover, a hybrid use of them, called hybrid-TOA/AOA (HTA), has also been proposed for performance improvement. However, when the direct wave is blocked by obstacles in the non-line-of-sight (NLOS) environment, the estimation accuracy is severely deteriorated. To coordinate this problem, an iterative minimum residual (IMR) scheme has been proposed for TOA-based estimation. In the IMR scheme, the NLOS nodes are sequentially detected and eliminated, and the estimation performance is improved. However, the IMR scheme for HTA measurements has not been considered. Therefore, in this paper, we propose a new NLOS detection scheme based on IMR scheme for HTA localization and evaluate its improved performances by computer simulations.

現状国内で運用する無人搬送車(AGV)は最高走行速度を60m/minと制限しているのが現状である。ダイフクでは、最高速度を200m/minのAGVを開発し、安全技術開発に取り組んだ。作業者の安全を確保しつつ、生産性の向上を目指している。最高走行速度200m/minの高速ビークルは、安全対策としては障害物センサー、ソフトバンパー(本体全周)、進行方向表示器、非常停止装置の装着で、既存のビークルと同様の構成である。これだけでは、安全を確保できないので、安全を確保する為に次の3点の開発を行った。(1)3D障害物センサーの開発、(2)エリア管理システム、(3)ローカルエリアセンサを開発これらを組み込み実際の配送センターで実証テストを行い、これらを基に新JISへの提言を一般社団法人産業車両協会へ行う。

This study describes a method for evaluating the change in the water content of leaves by using visible and near infrared spectral analyses. The spectral behaviors within the 400-1100 nm region that corresponded to drought in the sample leaves were investigated using a spectrometer. Bands in the 470-490, 600-620, and 650-690 nm regions that are due to chlorophyll absorption were identified. Importantly, these bands were blueshifted by about 6-9 nm and showed decreased intensities. In particular, the band in the 650-690 nm region correlated to the water content with a coefficient of determination (R2) of 0.74. The spectral patterns of the loadings, which were calculated by principal component analysis (PCA), appeared similar to those of the second derivative spectra. Furthermore, the score of the first principal component obtained by PCA was clearly separated at the water content value of 48.1%. Therefore, the results provide a chemical understanding of band behavior in the 400-1100 nm region and suggest that PCA may support the evaluation of water content and stress in leaves by using this spectral region.

In order to improve a power assist mechanism for one hand use wheelchair developed in our research group, a wheelchair with some sensors has been constructed. By using this wheelchair, torques given by human through handrims and the velocity of wheelchair have been observed on flat course and on slope. Observed data shows that human's body weight shift in wheelchair running is related to the movement of wheelchair. We consider that attention to this fact is useful for investigating effective power assist scheme.

Focusing our attention mainly on the shape quality of formed cups, the conventional cylindrical cup-drawing and the stretch-drawing processes with or without ironing are carried out. Four materials including titanium are tested. The shape quality of the products is represented by the uniformity of the wall thickness and the roundness of the cup cross-section. A new index, the distortion index, is introduced to evaluate the lack of roundness. Comparing with the cups formed by the conventional deep-drawing, the effects of the stretching and ironing on the shape quality are investigated in detail. As a rule, the stretching as well as the ironing makes the wall thickness to distribute more uniformly. Broadly speaking, the roundness of the cup is improved by the accompanied ironing with the reduction in thickness. This is not necessarily true for the stretching. However, the complete ironing does not improve the roundness of the copper cup. Typical shapes of the distorted cup cross-section are demonstrated, such as are oval, square, cross and others. For the deep- and stretch-drawing, the cup distortion pattern is related to the planar anisotropy of the tensile material properties. This is not the case for the ironing.