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Publisher：Journal of Ocean Engineering and Marine Energy  

This paper focuses on the issue of accuracy degradation when directly constructing a reduced-order model (ROM) using dynamic mode decomposition for a volume of fluid (VOF) field of two-phase flow simulations, and proposes a improved method that utilizes the signed distance function (SDF), also known as the level set function, with respect to the gas–liquid interface. The effectiveness of the proposed method was demonstrated by applying it to sloshing tank problems under two different conditions. The oscillation modes were observed to appear only near the interface when using the VOF field directly; however, the influence of the interface is alleviated over a larger distance, resulting in smoother oscillation and improved performance of the ROM when employing the level set function. The results show that ROM for a level set function in cases with small oscillation was shown to be effectively equivalent to that for one-dimensionalized interface. Moreover, the ROM of the level set function could reproduce the physics of this phenomenon with higher accuracy than that of the VOF fields in the cases where one dimensionalization is not possible, such as when the liquid inside the tank surges and climbs up to the ceiling.

DOI： 10.1007/s40722-025-00385-x

Web of Science

Scopus

Publisher：IEEE Sensors Letters  

We propose an anomaly detection method based on modal representation and a noise-robust sparse sensor position optimization method. We focus on the detection of anomalies in global sea surface temperature field observations indicative of El Niño and La Niña phenomena. For evaluation, we compared four methods, namely, the random linear least squares estimation method, the determinant-based greedy linear least squares method, the DG with noise covariance generalized linear least squares (DG/NC-GLS) estimation, and the Bayesian DG Bayesian estimation (BDG-BE) method of which the extension is proposed in this study. The results demonstrate that the DG/NC-GLS and BDG-BE methods outperform the other methods in anomaly detection. In fact, the DG/NC-GLS and BDG-BE methods achieve high accuracy and precision of over 81% with only 20 sensors (44 219 sensor candidates) for anomaly detection in global sea surface temperature field observations.

DOI： 10.1109/LSENS.2025.3591066

Web of Science

Scopus

Publisher：Experiments in Fluids  

Visual feedback control of a flow field by a controller that operates plasma actuators with sparse processing particle image velocimetry as an observer was implemented in a wind tunnel test. The control objective was the suppression of a Kàrmàn vortex around a circular cylinder. Sum-of-absolute-values control based on an L1 optimization problem was implemented to enable real-time processing. Real-time visual feedback control at 2000 Hz was achieved with the proposed system owing to the use of sparse processing particle image velocimetry, which evaluates only a limited number of interrogation windows, and a sophisticated solver for the L1 optimization problem. The techniques adopted in the present study can accelerate the feedback control rate by a factor of 10 to 100. It was confirmed that the proposed system suppresses the Kàrmàn vortex to a certain extent. The results show that the control law using forecasts further ahead performs better.

DOI： 10.1007/s00348-025-04039-4

Open Access

Web of Science

Scopus

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/JSEN.2025.3537702

Web of Science

Scopus

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Publisher：Actuators  

This study investigated the effectiveness of a dielectric barrier discharge (DBD) plasma actuator operating in burst-in-burst (BIB) mode for flow separation control on a NACA 0015 airfoil. Time-resolved particle image velocimetry measurements were conducted at a Reynolds number of 66,000 and 13° angle of attack. Various BIB signal configurations were tested, with actuation periods of 70 ms and 150 ms, non-actuation periods ranging from 5 ms to 50 ms, and burst frequencies of 300 Hz and 600 Hz. Proper orthogonal decomposition was applied to analyze the flow field dynamics. The results showed that BIB actuation maintained flow attachment with reduced power consumption compared with continuous burst actuation. However, the effectiveness was highly sensitive to the BIB parameters, with some configurations failing to achieve consistent reattachment and becoming unstable. This study reveals complex interactions between actuation vortices and separation processes, highlighting both the potential and challenges of intermittent plasma actuation for efficient flow control.

DOI： 10.3390/act13110435

Open Access

Web of Science

Scopus

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)   Publisher：The Society of Instrument and Control Engineers  

DOI： 10.11499/sicejl.59.546

CiNii Research

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Event date： 2025.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2024.9

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Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2023.10

Language：Japanese   Presentation type：Oral presentation (general)  

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