電力線通信技術を用いた革新的な部分放電監視システムの開発

九州工業大学九州工業大学博士学位論文（要旨）学位記番号: 工博甲第602号 学位授与年月日:令和7年3月25日thesi

凸多面体の重なりを持つ／持たない展開図

九州工業大学九州工業大学博士学位論文（要旨）学位記番号: 情工博甲第408号 学位授与年月日:令和7年3月25日thesi

Space-Efficient B Trees via Load-Balancing

We study succinct variants of B trees in the word RAM model that require s + o(s) bits of space, where s is the number of bits essentially needed for storing keys and possibly other satellite values. Assuming that elements are sorted by keys (not necessarily in the order of their integer representations), our B trees support standard operations such as searching, insertion and deletion of elements. In some applications it is useful to associate a satellite value to each element, and to support aggregate operations such as computing the sum of values, the minimum/maximum value in a given range, or search operations based on those values. We propose a B tree representation storing n elements in s + O(s/lg n) bits of space and supporting all mentioned operations in O(lgn) time. Operations on integer-ordered keys and satellite values can be accelerated to O(lg n/lglg n) time if we use s + O(slglg n/lg n) bits of space. The time is retained for special kind of aggregate functions that can be computed bit-parallel in constant time. For integer-ordered keys, we can also compress the space s to match compression measures using difference encoding of the keys while retaining the operational time complexities. For the last enhancement, we allow us to pre-compute tables of o(n) bits.journal articl

Migration Characteristics in Pool-and-Weir Fishway with Single and Multiple Fish Species

魚道に単一魚種を放流して遡上率を算出し，適切な魚道規格を求めた研究は多数存在する．ところが，現地魚道では複数魚種が混在した状態で遡上に挑んでいる．本研究では階段式魚道内でアユ，オイカワ，ドジョウが単一または混在魚種状態での遡上実験を行った．その結果，単一魚種では各魚種が好む流速場で魚群を形成し，遡上に挑む．混在魚種状態ではアユは低流速域に移動し，オイカワ，ドジョウはアユの魚群から離れた領域に押し出される．オイカワの一部は切欠きからの高速落下流にしばしば接触することおよびアユから忌避のため，遡上率が向上する．アユ，ドジョウは他魚種の存在に注意を払い，遡上に挑まない．Many experiments have been conducted to determine the optimum fishway standard on the basis of the migration rate of a single fish species released near the entrance of a fishway. However, fish try to migrate in the fishway surrounded by other fish species. In this study, the migration experiments in the pool-and-weir fishway were conducted as single or multiple species of Plecoglossus altivelis, Opsariichthys platypus and Misgurnus anguillicaudatus. In the single species condition, each species formed a school of fish at its preferred velocity and attempted to migrate upstream. In the multiple species condition, all fish species changed their schooling position as compares with that of single species. The school of P. altivelis moved to the low velocity zone, while O. platypus and M. anguillicaudatus were pushed away from the P. altivelis school. On the other hand, O. platypus are pushed into the high speed velocity area and become more motivated to migrate upstream.journal articl

Suitable Aperture Shape of Fish Nest Blocks for Rest of Plecoglossus Altivelis, Opsariichthys Platypus and Nipponocypris Temminckii

魚がすめる川の条件の一つに避難場所の確保があり，その一手法に魚巣ブロックの設置が挙げられる．ところが，魚巣ブロックの推奨規格は未解明である．本研究では魚巣ブロックの開口部形状を，全面，上流側，下流側，水面側および底面側開放の5種類に変化させるとともに，主流の体長倍流速を3，6，9(1/s)に変化させてアユ，オイカワ，カワムツの挙動を観察した．その結果，魚巣ブロックの開口部下辺が主流底面と接する場合に全魚種で利用回数が高く，この場合オイカワおよびカワムツは速やかに進入する．アユは警戒心が強いため進入までに時間を要する．また，全面開放および底面側開放では全魚種で利用回数が増加する．One of the conditions for a fish-friendly river is the provision of shelter, and one method of securing shelter for fish is the installation of fish nest blocks. Various studies have been conducted on fish nest blocks, and it has been found that fish nest blocks are useful as resting places for fish when they become fatigued and as shelter from external factors. In this study, the effects of aperture shapes (full open, upstreamopen, downstreamopen, top open, and bottom open) and velocity divided by body length (3, 6 and 9 (1/s)) on the resting characteristics of Plecoglossus altivelis, Opsariichthys platypus and Nipponocypris temminckii were examined. As a result, in the case where the aperture was secured on the bottomside, it was found that fishes can enter the fish nest block easy, and quickly. Spending time in the full open and bottom open fish nest blocks is longer than that of another one.journal articl

Error-Related Potential During Cooperative Exploration by Humans and Robots in a Large-Scale Maze and the Effect of Boredom on It

In future, humans live with autonomous robot, and cooperate with it. In this study an autonomous robot and a human were asked to cooperate in an exploration task to reach a goal in a large-scale maze. While they were doing a task, electroencephalogram (EEG) was measured from the human. The human was asked to choose the direction of travel at intersections, and 30% of the choose, the robot traveled in a different direction from that specified by the human. Error-related potentials (ErrPs) occurred in the human brain at the time, and that was consistent with that reported in the previous studies. Time-frequency analysis of EEG revealed an increase in θ-frequency power and a decrease in β-frequency power. Some participants felt “bored” during the task. As if to reflect this, in the second half of the task, the amplitude of ErrPs decreased and θ-frequency power also decreased. When the ErrPs of the first and second halves were discriminated using a convolutional neural network, the accuracy rate of the correct responses decreased in the second half compared to the first half. These results suggest that ErrP changes with boredom, and there is a possibility to detect the boredom using EEG.journal articl

ハンドクラフト特徴量による深層学習ベースの三次元物体検出器の性能向上

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Data assimilation between Monte Carlo simulation and experimental results of crystal growth island density in REBCO thin films during the initial growth stages

YBCO superconductors offer high transition temperatures for applications. REBCO wires, made via pulsed laser deposition (PLD), are developed for various uses. However, optimizing PLD parameters is time-consuming. To resolve this, we aimed to develop the simulation of REBCO thin film growth with Monte Carlo algorithm and Bayesian optimization to find the optimal parameters. While current simulations show discrepancies with experiments, this approach sets the foundation for improved models and simulations.journal articl

Fuzzy Sentiment Analysis for Hand Gesture Interpretation in Words Expression

This paper will discuss the interpretation of hand gestures using words with the fuzzy sentiment analysis approach in the tea-tasting experiment. In the experiment, participants were asked to drink tea, give a hand gesture, and choose three words that could interpret the hand gesture. The results show that hand gestures cannot be categorized as fixed sentiment labels, considering the meaning can differ depending on each preference. Generally, traditional sentiment categorizes labels as positive, negative, or neutral, which fails to capture human preferences. Therefore, we propose that the fuzzy sentiment model be used to solve the traditional problem, which provides a more flexible approach. Our findings show that interpreting hand gestures such as positive is not always positive but can be neutral-positive and vice versa. The results show that hand gestures alone are insufficient to determine sentiment; word expression is required to capture sentiment's different and complex aspects.journal articl

Comparative Study of Reinforcement Effects of Different Herbaceous Plant Roots on Fine-Grained Soil

This study investigates the reinforcement effects of the roots of three herbaceous plants—Kentucky bluegrass, Red fescue, and Hard fescue—on the shear strength of fine-grained soil. A series of direct shear tests were conducted to evaluate how root penetration influences the shear behavior and structural stability of root-soil composites. Results indicated that root-reinforced specimens demonstrated greater ductility, with shear stress increasing in later stages of shearing, thereby contributing to soil stability. Quantitative analysis revealed that Kentucky bluegrass roots increased cohesion by 2.29 kPa and the internal friction angle by 2.6°, while Red fescue roots increased cohesion by 2.84 kPa with a slight reduction in the internal friction angle by 0.35°. For Hard fescue, cohesion increased by 3.03 kPa, with the internal friction angle decreasing by 1.54°. These findings showed that root reinforcement varied significantly under different vertical stress conditions, emphasizing the importance of environmental factors in soil behavior assessment. Comparative analysis demonstrated that each plant species exhibited unique reinforcement effects under both low and high vertical stress, providing valuable insights for designing ecological slope stabilization solutions aimed at enhancing soil stability and promoting environmental sustainability.journal articl