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Gaze analysis of a walker user for the development of a gaze-based interface to operate a robotic walker
Get PDFAs populations in advanced economies continue to age and birth rates decline, a growing shortage of caregivers has emerged. This shortage has led to an inability to meet the demand for rehabilitation through human caregivers, prompting research into the automation of rehabilitation, such as robotic walkers. Estimating the user’s intent in a robotic walker can improve safety and provide intuitive control, as well as personalized assistance, thus reducing the psychological barriers users may face when interacting with the robot. This study aims to investigate the intention of direction change based on head orientation by analyzing gaze patterns during turning and while checking the surroundings. Gaze analysis was performed using the Tobii Pro Glasses 3. Participants were asked to perform a task involving both turning while navigating a specific route and checking numbers placed around them, allowing for the collection of gaze data. The collected gaze data were analyzed using three machine learning models: Random Forest, LightGBM, and SVM—which are capable of handling high-dimensional datasets and are expected to achieve high classification performance. Using gaze data collected during surrounding check tasks and direction change tasks, a classification model was trained to distinguish between surrounding check behavior (Class 0) and direction change behavior (Class 1). As a result, the Random Forest model achieved a classification accuracy of 99.5%, the Light-GBM model 99.8%, and the SVM model 99.4% for healthy participants, consistently demonstrating high accuracy. For patients with Parkinson’s disease (PD), the model trained on healthy participants could not be directly applied. Still, an attempt to improve SVM classification accuracy by adjusting the threshold using the decision function resulted in a classification accuracy of 64% at a threshold of 0.5.journal articl
超高強度薄鋼板の微視組織と遅れ破壊特性との関係に関する研究
Get PDF九州工業大学博士（工学）1 序論| 2 DP 組織の超高強度薄鋼板における定荷重試験による遅れ破壊挙動| 3 DP 組織の超高強度薄鋼板における遅れ破壊特性に及ぼす異相界面の役割| 4 残留オーステナイト相を有する超高強度薄鋼板の遅れ破壊挙動| 5 析出強化型フェライト単相超高強度薄鋼板の水素脆性| 6 析出強化型フェライト単相超高強度薄鋼板における水素と塑性変形の連続相互作用| 7 総括九州工業大学博士学位論文 学位記番号:工博甲第615号 学位授与年月日:令和7年9月25日令和7年度doctoral thesi
物質科学における時系列データの機械学習解析手法開発と応用：隠れマルコフモデルを用いた量子ドットおよび蛍光修飾DNAの蛍光時系列データ解析
Get PDF九州工業大学博士（工学）1 研究背景と目的| 2 研究手法| 3 結果と考察| 4 結論及び展望| 5 付録九州工業大学博士学位論文 学位記番号:工博甲第604号 学位授与年月日:令和7年3月25日令和7年度doctoral thesi
Simulation Platform for GaN-Based Three-Phase Voltage Source Inverter Analysis: Switching Frequency and Deadtime
Get PDFWide bandgap (WBG) devices have emerged as an alternative solution to silicon-based devices in many applications, considering the possible design and construction of converters with lower power losses, higher power density, and the ability to operate on high switching frequency. However, straightforward drop-in-replacement of the devices cannot provide the optimum desired performance. A simulation platform is essential for optimal design and system development. This paper presents the study of the development platform for a GaN-based three-phase 2-level voltage source inverter (VSI) system and analysis considering switching frequency and dead time. A modelling platform utilizing GaN enhancement mode power transistor EPC2016 was developed for the 3-phase VSI system. GaN-based 3-phase VSI system was analyzed for 60 V DC input using the modeling platform at different switching frequencies (50 kHz, 75 kHz, 100 kHz, 125 kHz) under deadtime conditions of 70 ns, 50 ns and 30 ns. Additionally, the system is investigated for the sinusoidal PWM (SPWM) and space vector PWM (SVPWM) techniques for all the cases.journal articl
Snapback in diamond p-i-p structure containing a small amount of n-type impurity in the i-layer
No full textWe studied the snapback phenomenon observed in a diamond p-i-p structure in detail and investigated the effect of n-type impurity concentration in the i-layer. The snapback observed in the p-i-p structure was also observed in the p-i-p structures with a very small amount of n-type impurity contained in the i-layer and in the p-n-p structure. The voltage at which snapback occurred (threshold voltage) varied with the n-type impurity concentration in the i-layer. A higher n-type impurity concentration resulted in a higher threshold voltage. These findings indicate that n-type impurities are associated with the occurrence of snapback. Additionally, there is a correlation between the threshold voltage and the substrate temperature: as the substrate temperature increases, the threshold voltage decreases. Furthermore, a high n-type impurity concentration in the i-layer results in a low leakage current. These results suggest that snapback in a diamond p-i-p structure is induced by a small number of n-type impurities in the i-layer, along with parasitic bipolar operation caused by the high applied voltage and increased leakage current.journal articl
On the FullMesh Path Selection of Multipath TCP Video Streaming
Get PDFVideo streaming makes most of Internet traffic nowadays, with most video applications transported over Hypertext Transfer Protocol/Transmission Control Protocol (HTTP/TCP). Being the predominant transport protocol, TCP stack performance in transporting video streams plays an important role, especially with regard to MultiPath Transport Control Protocol (MPTCP) and multiple client device interfaces currently available. One overlooked aspect of multipath transport is the management of all possible paths between sender and receiver endpoints. In this paper, we study the usage of all possible paths created by MPTCP vis a vis video streaming performance on wired networking environments. We show that a fullmesh path usage may result in degraded video streaming performance due to common bottlenecks between paths under a simple (default) path scheduler. We then propose a bottleneck aware path scheduler, and show its superior performance on various multipath scenarios. Our results cover both Bottleneck Bandwidth and Round-trip (BBR) propagation time TCP variant, as well as CUBIC variant in transporting video streams over wired networks. We use network performance level, as well as video quality level metrics to characterize quality of video streaming over TCP variants.journal articl
Intrinsic Disordered Network in Multiferroic YMnO3 Single Crystals for In-Materio Physical Reservoir Computing Through Tuneable Domain-Wall Structure
Get PDFPhysical reservoir computing (PRC) is an innovative computational paradigm that leverages intrinsic nonlinearity of physical systems to efficiently perform complex tasks. It is discovered that the intrinsically disordered domain structure in multiferroic YMnO3 provides significant nonlinearity, making it a promising candidate for robust PRC with tuneability and functionality at high temperatures. This work explores the potential of YMnO3 single crystals for PRC. PRC performance of YMnO3 is systematically evaluated by analysing its nonlinear responses, phase shifts, and high dimensionality through benchmark tasks such as waveform generation (WG), memory capacity (MC), and second-order nonlinear autoregressive moving average (NARMA2) time-series prediction. This results demonstrate that YMnO3 single crystals exhibit superior performance in these tasks, achieving high accuracy and low power consumption (≈1.77 µW and ≈0.02 nW/domain). These crystals also performed well in practical application of low-power speech recognition. These findings establish YMnO3 as a viable platform for next-generation PRC technologies, addressing critical challenges in the field.journal articl
Migration Characteristics in Pool-and-Weir Fishway with Single and Multiple Fish Species
Get PDF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