IEEJ Transactions on Electrical and Electronic Engineering最新文献

The purpose of this paper is to establish a heat transfer simulation method for magnetic hyperthermia that incorporates the heat generation characteristics of low curie point thermo-sensitive magnetic particles and their relative position to a Drive coil that applies the magnetic field. We developed a method for estimating heat generation based on the magnetic permeability of the thermo-sensitive magnetic particles and the magnetic field distribution of the Drive coil. Additionally, we measured the temporal change in heat generation through two physical experiments that varied the agglomeration density and distribution shape of the thermo-sensitive magnetic particles. The results demonstrated that the proposed simulation method could replicate the experimental results with an average error of 0.7% and 1.3%, respectively. Furthermore, physical experiments and heat transfer simulations show that the maximum heat generation of the thermo-sensitive magnetic particles increases linearly with increasing agglomeration density and with increasing base area of the distribution shape. © 2025 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

With the growing environmental awareness, electric vehicles (EVs), as flexible and mobile load resources, have gradually enhanced their optimization and regulation capabilities in power systems. However, the subjectivity and unpredictability of users' trip plans in special circumstances significantly impact the dispatching results of EV clusters. To address this issue, this paper establishes a real-time trip chain correction model that integrates power and traffic networks to simulate the distribution of EV charging loads under spatiotemporal reconfiguration. Furthermore, considering the dispatchable potential of EVs after trip completion, a user behavior decision-making method is proposed. This method utilizes fuzzy control to analyze EV charging demand and quantifies the degree of user responsiveness to the dispatching strategy. Then, based on the charging urgency index, a coordinated dispatching strategy is introduced to mitigate grid fluctuations, reduce peak loads, and lower user charging costs. Finally, experiments analyze the effects of spatiotemporal reconstruction and decision-making behavior on the EV dispatching process. Results demonstrate the effectiveness of the proposed strategy in reducing users' charging costs while achieving peak load reduction and valley filling in the power grid. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Transcutaneous vagus nerve stimulation (tVNS) through auricular points emerges as a potential solution for mitigating depressive symptoms. This paper presents the development and evaluation of a button-style transcutaneous auricular vagus nerve stimulation (taVNS) device for portable treatment and research applications. The device integrates photoplethysmography (PPG) for heart rate variability (HRV) monitoring, enabling real-time evaluation of autonomic nervous system functionality. The system incorporates a user-friendly design, including an Android application for monitoring HRV metrics and adjusting stimulation parameters, ensuring accessibility and personalization. In an initial evaluation involving nine volunteers, five participants demonstrated significant improvements in autonomic nervous system functionality, as evidenced by enhanced SDNN values, while four participants showed minimal response. These results confirmed the usability of the closed-loop device and could potentially enhance future research efforts in personalized taVNS therapy. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

With the progress of science and technology, the application of dry-type transformers in distribution networks is increasing day by day. However, the problems of short-circuit heat, bias heat, and overload heat in the operation of dry-type transformers will pose a threat to the service life and insulation performance of transformers. The finite element simulation of temperature rise in dry-type transformers has drawbacks such as long calculation times and high memory usage. To solve this, this paper presents a rapid method for calculating the temperature rise during interturn short-circuit fault (ISCF). A 3D reduced order model for the temperature rise of the dry-type transformer ISCF is developed. This model enables the rapid calculation of hotspot temperatures. The ISCF experiment was conducted on a customized dry-type transformer. The feasibility of the reduced order method was verified by comparing the experimental results with the simulation results. The application of model order reduction can simplify the model to the required error, speed up the simulation, and serve as a reference for improving the efficiency of digital twin technology in dry-type transformers. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

The Elderly-Care Robot (ECR) addresses the aging population issue by assisting elderly individuals with recognition, tracking, and companionship, easing the burden on healthcare systems and families. Its person-following functionality consists of visual tracking and visual servo components. Current visual tracking algorithms face challenges like occlusion and limited computational resources. This paper proposes a robust tracker for embedded systems by combining Kernelized Correlation Filter (KCF) and Kalman Filter (KF). The approach utilizes the Average Peak-to-Correlation Energy (APCE) index to detect occlusions and adapt the learning rate accordingly. For visual servoing, an image-based visual servo control algorithm is developed to estimate the robot's position and guide its movement using monocular vision. Experiments on datasets show improved occlusion handling and real-time performance with an overlapping success rate of 0.602 on OTB-100 and 0.247 on LaSOT. In addition, real-world tests demonstrate the robot's effectiveness in tracking and maintaining distance to a target in an obscured environment with a tracking speed of 0.586 m/s, while maintaining a safe distance of 2.36 m, achieving an 87% success rate. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

The stable operation of wind farms is important for achieving sustainable development and environmental protection. To understand the wind and ice response characteristics of the terminal tower-line system in a wind farm. A spatial finite element model of the terminal tower-line system of a 35 kV wind farm was established, and the harmonic superposition method was employed to simulate the fluctuating wind load time history of the system. By superimposing static wind loads, the characteristics of the wind-induced vibration response and the dynamic stability of the ice-covered tower-line system under different wind direction angles were analyzed. The results indicated that, compared to a single tower structure, the tower-line coupling effect has a more significant impact on the wind-induced vibration response of the terminal tower-line system. The most unfavorable wind direction is perpendicular to the conductor arrangement, and the maximum stress on the tower occurs on the windward side where the conductor is attached. The tension of the conductor has the greatest impact on the terminal tower, and this effect is further amplified by conductor icing and galloping. Finally, a method is proposed to assess the dynamic stability of terminal tower-line systems based on yield criteria. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Weld defects on steel structural members can significantly impact the members' quality. Therefore, it is essential to detect these defects. This study created a dataset by capturing images of weld defects using X-ray nondestructive testing technology. Then, an enhanced You Only Look Once version 5 s (YOLOv5s) algorithm was developed by incorporating Coordinate Attention (CA) attention, replacing the original C3 with GhostC3, and replacing the original complete intersection over union (CIoU) with focal-efficient intersection over union (EIoU). Experiments were conducted using the dataset. The results showed that the CA attention mechanism utilized in this study outperformed squeeze-and-excitation attention and other attention mechanisms in weld defect detection. The improvements made to other components also contributed to improved precision and speed. Compared to the single shot multibox detector, the You Only Look Once version 8 s (YOLOv8s) algorithm, and other algorithms, the enhanced YOLOv5s model achieved a detection speed of 24.56 frames per second and a mean average percentage of 96.72%, demonstrating the best overall performance. These results validate the reliability of the enhanced YOLOv5s algorithm for weld defect detection and its potential practical applications. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Muscle fatigue significantly impacts the accuracy of force estimation, posing a challenge for the long-term use of myoelectric interfaces. In this study, we propose a novel transfer learning-based method to enhance force estimation accuracy during muscle fatigue. The approach involves pretraining a force estimator using electromyography (EMG) data from the non-fatigue state and fine-tuning the model with data from the fatigue state. A deep end-to-end convolutional neural network was employed as the force estimator, eliminating the need for hand-crafted features and enabling direct learning from raw EMG signals. The results demonstrate a 75% reduction in the root mean square error (RMSE) of force estimation during muscle fatigue using the proposed transfer learning algorithm. Furthermore, the influence of target training dataset size on transfer learning performance was systematically analyzed, providing valuable insights into optimizing model adaptation. This study highlights the effectiveness of transfer learning in mitigating the effects of muscle fatigue on EMG-based force estimation, enabling the reliable, long-term use of myoelectric interfaces. The findings have significant implications for improving the functionality and convenience of prosthetic devices, ultimately enhancing user satisfaction and quality of life. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

In this paper, we design algorithms of a linearization and a nonlinear filter for time-varying systems using a pseudo-formal linearization based on Chebyshev interpolation. Presented algorithms make it easy to linearize nonlinear time-varying systems and to synthesize a nonlinear filter. They can also reduce the computational burden in both linearization and estimation processes by exploiting Chebyshev interpolation. This algorithm applies a Kalman filter to each linearized system, which is obtained in a some subdomain by using pseudo-formal linearization, to construct a nonlinear filter that is valid for the entire domain. We demonstrate the effectiveness of algorithms through demonstrating numerical experiments with linearizations and a nonlinear filter of an academic bioreactor. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

The off-grid system (OGS) has relatively low voltage and frequency requirements, making it suitable for renewable energy generation modes such as wind and solar power. However, due to the large volatility of the power from the generation side and the upper-bound constraints on its energy supply capacity, OGS faces issues such as low energy utilization efficiency, weak generation-load power matching, and poor system economic performance. To address these challenges, flexible management on the load side is necessary to achieve optimal operation of generation-load power balance. This paper establishes a bi-level optimization model for OGS, incorporating renewable energy power plant (REPP), shared energy storage plant (SESP), and load aggregator (LA), based on master-slave game theory. The model is solved using a combination of Adaptive Differential Evolution (ADE) algorithm and the CPLEX solver. Through simulation examples, the results show that the integration of SESP into the system alleviates the issue of generation-load power mismatch, reducing the OGS's curtailment of electricity by 34.15%. This significantly improves the energy utilization efficiency, while the net profit of the REPP increases by 68.62% and the net profit of the LA rises by 6.59%, effectively achieving a win-win situation among all the stakeholders. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.