Tobishima (Japan)

Sound field visualization is effective for intuitive evaluation of the field. To visualize the sound field, various methods and systems have been studied and proposed such as acoustic holography, optical methods, and sound intensity visualization. Especially, the musical field visualization is effective for evaluating musical performance, supporting hearing-impaired persons, and inspiring artistic expression. In this study, we use the sound field visualization system “OTOMIRU®.” The system consists of a 16ch microphone array, measurement system on PC, and visualization system on XR (extended reality) devices. The measurement system analyses sound sources recorded from the microphone array using the MVDR (minimum variance distortionless response) beamforming method. The analysis results are sent to the visualization system by TCP (transmission control protocol). Finally, the results are visualized as colormap-like thermography and superimposed on the real world on XR devices. The system is mainly used for noise visualization, detection, and countermeasure of construction sites or indoor spaces. To visualize the musical field, we applicate the system to visualize not only sound pressure levels but also other acoustical parameters such as frequencies. To visualize these parameters, sound field information can be detailed and comprehensible. We show the efficiency of the visualization and its applicability to other situations.

Due to their low cost, most river embankments in Japan are Earth-mound embankments. However, Earth-mound embankments frequently burst due to heavy rains caused by typhoons and linear precipitation bands. Therefore, there is an urgent need for low-cost robust river embankments for water overflows that are more resistant to collapse. Since the most common reason for embankment failures is the infiltration of overflow water, a robust embankment with a crushed shell capillary barrier (CB) is proposed to reduce the infiltration of overflow water. To develop technologies for robust river embankments, measuring and quantifying overflow water are necessary, and the Ministry of Land, Infrastructure, Transport and Tourism of Japan (MLIT) recommended validating technologies using artificially constructed hydraulic measurement setups, referred to as pseudo embankments hereafter. In this article, as part of the development of a robust embankment with a shell CB, an overflow velocity measurement system using millimeter-wave multiple-input multiple-output (MIMO) radar is presented. A real-size pseudo embankment is fabricated, and overflow velocity measurements are conducted using this pseudo embankment. The experimental results demonstrate the effectiveness of the velocity measurement system using a millimeter-wave MIMO radar. The results show that the proposed system is capable of monitoring overflow velocities effectively over the entire pseudo embankment and has the potential to grasp the status of embankments intuitively from the reflection point clouds obtained by radar. Moreover, a comparison between the velocities measured by the proposed millimeter-wave MIMO radar system and those measured by the camera system using image processing is also provided in this article. As a result, the proposed system using a millimeter-wave MIMO radar has higher accuracy and lower computational complexity.

記録的大雨に伴う堤防決壊が頻発化する近年，粘り強い堤防が求められている。筆者らは，堤防裏法面に破砕貝殻層を敷設することで，キャピラリーバリア（CB）土層として裏法面への雨水浸透抑制と，越水時の裏法面の侵食抑制が可能な貝殻型 CB 堤防を提案してきた。本研究では貝殻型 CB 堤防の社会実装を目指し，堤防裏法面の CB 機能に関する検証と妥当性確認を目的とする。貝殻型 CB 堤防を屋外に構築し，雨量計と堤防内の土壌水分センサによる雨水浸透の計測を約 1 年3 か月継続した。その結果，CB 土層の雨水浸透抑制機能に加え，ブレークスルー後でも浸透水の多くが高透水性の破砕貝殻層を伝って法尻方向に排水されていく排水機能も併せ持つことも確認された。また，ブレークスルーが生じてもしばらくすると回復したことが繰り返し確認され，CB 機能等が供用中の長期間に渡り継続していくことが検証できた。

ObjectivesThis study aimed to examine the long-term effects of parenting practice during preschool years on children’s movement performance in primary school.MethodsThis three-year longitudinal study included 225 children aged 3–6-years-old. Parents reported baseline parenting practice and evaluated children’s movement performance three years later. Latent class analysis was used to explore latent classes of movement performance. A post hoc test was used to identify the characteristics of different patterns. Finally, adjusted multinomial logistic regression models were used to test the influence of parenting practice on identified patterns of movement performance.ResultsChildren in this study were grouped into three movement performance patterns, labelled as ‘least difficulties’ (n = 131, 58.2%), ‘low back pain’ (n = 68, 30.2%) and ‘most difficulties’ (n = 26, 11.6%). After controlling for age, gender, having siblings or not, family structure, standardised body mass index, sleep condition and dietary habits, the researchers found that if parents played games with children frequently, the children would have a 0.287 times lower probability of being in the ‘low back pain’ class (95% confidence interval [CI]: 0.105–0.783). In addition, if parents take children to meet peers of a similar age frequently, children would have a 0.339 times lower probability of being in ‘most difficulties’ class (95% CI: 0.139–0.825).ConclusionPrimary healthcare providers should pay careful attention to children with movement difficulties. The study provides longitudinal evidence to support the applicability of positive parenting practice in early childhood to prevent children’s movement difficulties.

In an enclosed space such as a particle accelerator tunnel, ensuring worker safety during a disaster is an issue of critical importance. It is necessary to have a system in which the manager can know from outside the tunnel whether there is any worker left behind and whether the worker is escaping in the right direction. Because a global positioning system (GPS) is not available in the tunnel, we are developing a disaster prevention system that uses Wi-Fi to transmit the positioning of workers and two-way communication. The Wi-Fi access point (AP) installed in the tunnel should be radiation resistant. Additionally, the equipment carried by the worker is convenient and easy to carry. We tested the radiation hardness of commercial AP devices and developed a smartphone application to perform location information transmission and simultaneous character transmission. In 2019, we installed the system on the J-PARC Main Ring and started its operation. In this paper, the functions of the developed system and its prospects are described.

本研究は、震災復興土地区画整理事業が施行されている区域を対象に、住宅再建に関する課題を提示することを目的としている。東日本大震災の発生によって施行区域の全部または大部分が津波浸水被害を受けた震災復興土地区画整理事業は19市町村・47地区で進められているが、震災から約7年半が経過した現在、住宅用地の区画数ベースの利用率は平均で43％であり、3分の2程度の地区では50％以上が空き地になっている。こうした状況を改善するためには、地権者と市町村が計画当初には思い描いていなかったはずの現実を出発点として、改めて将来のビジョンとその実現方策を検討することが必要である。

キャピラリーバリア（以下CB）は，降雨浸透制御技術の一つとして利用され，砂層と礫層の保水性や透水性などの違いにより，その機能が発揮される。これまで，室内レベルの土槽実験により，保水性やCB限界長の評価が行なわれてきているが，CB地盤を設計する上で，重要なパラメータである限界長を，数値シミュレーションにより評価した事例は見られない。本論文は，前記課題に対応するため，室内実験により得られている限界長の観測結果に対して，斜面CB層を有する浸透現象を2次元の数値シミュレーション（HYDRUS-2D）で再現できるかどうかを検討し，限界長と底部流出量分布に着目して数値シミュレーションの適用性を評価したものである。その結果，数値シミュレーションの結果は，実用可能なレベルで大型土槽の実験データに対する再現性を示すことができ，CB の設計に適用できる可能性を明らかにした。

Abstract In recent years, a lot of accidents associated with infrastructures occur in Japan because of the remarkable deterioration of the infrastructures. Considering the expected reduction of construction investment year after year, it is important to repair and reinforce those structures with the limited budget as well as to extend their service life in the future. From the viewpoint of management and maintenance for those ageing infrastructures, preventive maintenance shall be taken rather than the reactive maintenance. In the preventive maintenance, repairing and reinforcing structures shall be implemented before any fatal deterioration to the structures. However, the reasonable diagnostic method for preventive maintenance has not been established so far. NDT approaches to diagnose the early internal damage of structures is thus in high demand. To solve these issues, the authors had proposed “AE tomography” which executes both AE monitoring and elastic wave tomography. The AE tomography enables to provide accurate AE source locations as well as velocity distribution with the tomography simultaneously. In this paper, in order to verify this proposed AE tomography for in situ infrastructures, deteriorated RC bridge deck for bullet trains was investigated.KeywordsElastic WaveRayleigh WavePreventive MaintenanceDamage AreaWave TomographyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.