Search

The accurate estimation of the zigzag leakage flux losses (ZZLFL) caused by the slot harmonics and their interactions, which occupy a high proportion of stray losses, are of great significance in the efficiency calculation as well as the optimization design for the wet submersible induction machine (WSIM). In this paper, a two‐dimensional finite element method (FEM) is presented to separate ZZLFL into the iron losses and the eddy‐current losses. The air‐gap magnetic flux density is decomposed by the two‐dimensional fast Fourier transform at a sampling frequency of 5000 Hz. The hybrid excited virtual permanent magnet harmonic machine model is applied to reconstruct the air‐gap magnetic field and excite the stator and rotor separately. Each node harmonic iron losses are acquired through the modified Bertotti iron losses model with the consideration of high‐frequency power losses as a function of the magnetic flux density. The zigzag flux losses provided by different harmonics are obtained by subtracting the hybrid excitation losses. According to the different proportions of harmonic losses among zigzag flux losses, novel WSIM models are proposed in the paper to decrease zigzag flux losses and increase the efficiency. Adopting the same computation process, the novel models with different structures are explored and verified to improve the zigzag flux losses and power density. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a contemplate study on online voltage control strategy with different loading conditions in a DC microgrid using particle swarm optimization (PSO). DC microgrids consist of many converters and it is an important issue to stabilize network voltage by properly designing their controllers. Conventional feedback controls have been often used as a primary control for voltage stabilization with optimizing control parameters such as droop gains. Moreover, the optimal control parameters should be flexibly updated when the system condition dynamically changes so as to maintain high voltage control performance under sudden and unexpected changes in system conditions. In that context, this paper introduces an online voltage control using an advanced PSO technique to frequently update control gains. The primary control was modeled as a proportional‐derivative controller, and the optimization problem was defined based on the eigenvalue analysis. A parallel operation of local and global searches is conducted in the proposed method to search optimal control gains by allocating a part of particles to move in a random pattern. The validation of the proposed method was performed using a simplified 3‐bus DC microgrid model with two generator sets and two constant power loads. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The transformer is the most essential component in electrical power transmission. Once a transformer is installed, it is generally used for decades. When failure occurs in a transformer, serious problems can arise, and numerous electrical components that depend on the transformer may be affected. Thus, deterioration diagnosis of transformers is important. The furfural content in the insulating oil of a transformer is widely used as an indicator of transformer deterioration, as furfural is generated by decomposition of the insulating paper. Although the degree of transformer deterioration can be estimated by measuring the furfural content, this measurement is time‐consuming. This paper proposes a novel method for estimating the amount of furfural contained in insulating oil within a short time. The method is realized by combining spectroscopic analysis in the visible region with a pattern recognition technique. The effectiveness of the proposed method is verified through a series of experiments. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The activities of care are often regarded as intimate and highly dependent on personal, relational and cultural contexts of care provision. In this paper, I explore how migrant care workers who do not share in the cultural logic and norms understand and mediate the expectations of intimacy in care work with their personal meanings and values in caregiving. Through multiple in‐depth interviews with 50 Filipino care workers and 1‐month of intensive fieldwork in a long‐term care facility, this paper unpacks the meanings and negotiations of intimacy in the care work of Filipino migrants in Japan. This paper analyzes intimacy in four dimensions: spatial, cultural, corporeal, and relational. It finds that Filipina care workers understand and negotiate intimacy in the care of the elderly Japanese by embodying cultural intimacy, mediating vulnerability and maintaining boundedness, attuning with the aged body, and articulating familial care. The findings offer the possibility for transformative caring relations when migrant care workers exercise intimacy in their care of the elderly residents in the institutional setting. [ABSTRACT FROM AUTHOR]

The evaluation of the failure probability is essential in the reliability‐centered and risk‐based maintenance of power transformers. The breakage of the pressboard in disc‐type transformers is one of the critical factors determining the lifetimes of power transformers. In this paper, a hierarchical method for evaluating the probability of pressboard failure, which is the breakage of the pressboard, in power transformers that considers the axial displacement of the winding is introduced. In the method, the diagnosis of the axial displacement is classified into three distinct classes. In class 1, no diagnosis is implemented, and the probability of failure is evaluated with the maximum possible axial displacement. In class 2, the diagnosis determines whether the winding is axially displaced. When the winding is diagnosed to be displaced, the probability of failure is evaluated with the maximum possible axial displacement. In class 3, the axial displacement is diagnosed quantitatively, and the probability of failure is then evaluated using the diagnosis result. Examples of the evaluated probabilities of pressboard failure are introduced, and the extension of the evaluated lifetimes of power transformers via the diagnosis of winding axial displacement is demonstrated. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Particle swarm optimization (PSO) is a popular optimization technique known for its simplicity and effectiveness. This paper introduces a variant that achieves a better balance between exploration and exploitation, named DiPSO. DiPSO incorporates a novel strategy based on trends in mean distance between individuals for local exploitation control. Experiments on 29 benchmark functions demonstrate that DiPSO consistently outperforms the state‐of‐the‐art variant of PSO. Convergence analysis reveals that DiPSO achieves faster convergence and superior solutions. These results highlight the effectiveness of DiPSO in solving optimization problems. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a micro‐Doppler radar‐based method to classify common pedestrians and pedestrians texting on a smartphone (called a smartphone zombies). We used a micro‐Doppler radar to collect motion data of the gait of participants texting on smartphones while walking, and then generated time‐frequency distribution images (spectrogram images). They were input into a convolutional neural network (CNN) to classify gait patterns. Results using measured data confirmed that the classification accuracy exceeded 90%, validating the effectiveness of the proposed method. Furthermore, by applying feature visualization by Grad‐Cam, we found that the motion of the leg swinging has essential features for the classification of smartphone zombies. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea (OSA) is a common sleep disorder and is diagnosed by polysomnography (PSG) as the gold standard. However, PSG is a time‐consuming and costly test, and patients have to endure long waits before receiving a PSG test in a hospital. In view of this, portable and wearable screening tools for OSA prediction have been developed recently as a low‐cost and easy‐to‐use method. In this paper, an OSA detection model, based on regression approach, using unsegmented electrocardiography (ECG) signals is developed to directly estimate the apnea‐hypopnea index (AHI) value, which is the first report in the literature. In this manner, this work can provide more details of OSA assessment to users and doctors. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Multi‐port hybrid DC circuit breakers (MP‐HCBs) are rapidly developing due to their obvious advantages in economy compared to traditional two‐port hybrid circuit breakers (HCBs). However, most of the existing MP‐HCB topologies do not have the current‐limiting capability, and a large number of insulated‐gate bipolar transistors (IGBTs) are still needed in their main breakers. In response to the problems, a multi‐port current‐limiting hybrid DC circuit breaker (MP‐CLHCB) based on thyristors is proposed in this paper. MP‐CLHCB uses low‐cost thyristors instead of IGBTs, and suppresses the rise of fault current through current‐limiting branch. In an attempt to prevent the MP‐CLHCB from reclosing in a permanent fault and causing damage to the DC grid again, an adaptive reclosing scheme is also proposed. In this paper, the topology, operation stages, theoretical derivation, and parameter design of the MP‐CLHCB are provided. Finally, the performance of the MP‐CLHCB is verified and compared through simulations in PSCAD/EMTDC. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper compares the machine learning algorithm‐based prediction methods for the traction characteristics in linear traction induction motors operating at common working conditions, i.e. different slip and running velocity, with a symmetric or asymmetric secondary. These models provide a method for obtaining the dynamic characteristics in the motor that considers nonlinear effects. First, some analytical results for the prototype machine under different working conditions is calculated. Second, classification and feature extraction of traction characteristics results including thrust, transversal and vertical forces is made according to the different slip, running speed and lateral secondary displacement, and the results set is divided into training sets and test sets. Third, the prediction model established by different machine learning algorithms are analyzed and compared in principle. These algorithms in this paper mainly contain: artificial neural networks (ANNs), linear regression (LR), symbolic regression using GP, k‐Nearest Neighbour (kNN), random forests (RFRs). The machine learning algorithm‐based prediction methods are trained with the training set, and then the verified with the test set. Finally, this paper discusses the most optimal model for predicting traction characteristics. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Considering the difficulty of extracting bearing fault signals of pumping unit and the complexity of diagnosis, a bearing fault diagnosis method based on refined composite multi‐scale dispersion entropy (RCMDE) and Extenics is proposed. Firstly, RCMDE is used to extract the features of bearing data. Using Fisher Ratio to reduce the dimensionality of RCMDE features and select them. The selected RCMDE features are used as the feature parameters of the matter element models to construct the classical domains and node domain of the four matter element models, and build the matter element models of the four healthy states of the bearing. Finally, the sample sets to be tested are input into the four health state models to calculate the comprehensive correlation degree value. The fault diagnosis is realized according to the principle of maximum comprehensive correlation degree. The results show that the detection rate of the proposed method for the four health states of the bearing is 98.8%. In order to verify the superiority of the proposed method, the method proposed in this paper is compared with the fault diagnosis method based on the combination of MDE and extenics, and the results verify the superiority of the proposed method in this paper. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

As energy shortages and environmental pollution continue to worsen, household photovoltaics has gradually become an important part of household energy management. However, with the penetration rate of household photovoltaics increasing, the access of the high‐proportion household photovoltaics (HPHP) will seriously endanger the operation of the distribution network. Therefore, it is urgent to stabilize the voltage fluctuations after the HPHP connected to the grid. This paper proposes a high‐proportion household photovoltaic optimal configuration method based on integrated–distributed energy storage system. After analyzing the adverse effects of HPHP connected to the grid, this paper uses modified K‐means clustering algorithm to classify energy storage in an integrated and distributed manner. Then based on the modified particle swarm optimization (MPSO), the integrated and distributed energy storage system is configured to realize the voltage stability of HPHP. The analysis of the example shows that the method proposed in this paper can effectively improve the power quality. At the same time, it can achieve the goal of economic optimization, which can effectively solve the adverse impact of HPHP grid connection. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The low‐speed and high‐torque modular fault‐tolerant permanent magnet motor has the strong fault‐tolerant ability, and can make the motor output torque act on the load directly, and the system has the highest transmission efficiency, which is especially suitable for ship propulsion. In the electric ship direct‐drive propulsion system, the motor is the core of the power system. Because the motor is directly connected with the load, the intermediate buffer mechanism is canceled, so the smooth operation of the motor is put forward to higher requirements. Especially in some fault‐tolerant operations, the unbalanced radial force generated by the asymmetric operation may cause the motor to vibrate greatly, which will reduce the operational life of the motor and even bring new faults. In serious cases, the whole transmission system will be damaged. Therefore, it is necessary to study the vibration of the fault‐tolerant motor under different operating conditions. In this paper, the module combined stator fault‐tolerant permanent magnetic synchronous motor for ship direct‐drive propulsion is taken as the research object. Based on the Maxwell tensor method, the radial force wave expressions of the motor during regular operation and fault‐tolerant operation are derived, and the harmonic order and frequency, which have a significant influence on vibration are summarized. The radial force of the motor under different operating conditions with different control strategies is calculated by the finite element method, and the harmonic components are analyzed by the two‐dimensional Fourier transform. On this basis, the vibration of the motor and the mechanical strength of the rotor support frame are analyzed. The research results of this paper provide some reference for the subsequent vibration reduction strategies of fault‐tolerant motors. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Brushless doubly‐fed generator (BDFG) is a most promising candidate for the wind turbine due to its simple structure, high reliability, and low converter capacity. To improve space utilization and achieve higher power density, this paper proposes a new dual‐stator BDFG (DS‐BDFG), which provides two separated windings, namely, the power winding (PW) placed in the outer stator and the control winding (CW) placed in the inner stator. A cup‐shaped rotor sandwiched between the inner and outer stators consists of the short‐circuited coil and the salient‐pole core. The coupling between the PW and the CW is realized via the rotor based on the general airgap magnetic field modulation theory for electrical machines. A prototype of the DS‐BDFG with rated PW power of 7.2 kW is designed and optimized. The keys of this paper are the power equation derivation, the determination of pole/slot combinations, and the rotor optimization. The electromagnetic characteristics and unbalanced magnetic force of the DS‐BDFG are analyzed by 2D finite element analysis to verify the reasonableness of the proposed model. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Aim: In order to understand the digital divide among older adults during the coronavirus disease 2019 (COVID‐19) pandemic, we investigated the association between internet use and compliance with COVID‐19 preventive behaviors during the first state of emergency in Japan. Methods: A total of 8952 community‐dwelling citizens aged 75 years and above were asked about their preventive behaviors during the first state of emergency using a paper‐based questionnaire. Among them, 51% responded and were divided into internet users and non‐users. We used multivariable logistic regression models to estimate the adjusted odds ratios and 95% confidence intervals of internet use for compliance with preventive behaviors. Results: Approximately 40% of the respondents used the internet, and 9.29% used social media to collect COVID‐19‐related information. Internet usage was independently associated with compliance with using hand sanitizers, avoiding going out, avoiding eating out, avoiding traveling, getting vaccinated, and getting tested for COVID‐19; the adjusted odds ratios (95% confidence intervals) were 1.21 (1.05–1.38), 1.19 (1.04–1.37), 1.20 (1.05–1.38), 1.32 (1.15–1.52), 1.30 (1.11–1.53), and 1.23 (1.07–1.41), respectively. Exploratory subgroup analyses demonstrated that social media users might have shown early adaptation to newly recommended preventive behaviors during the first state of emergency. Conclusions: Results suggest that a digital divide exists, as evidenced by the varied compliance with preventive behaviors depending on internet use. Additionally, social media use may be associated with early adaptation to newly recommended preventive behaviors. Therefore, future studies regarding the digital divide among older adults should investigate differences depending on the types and content of internet resources. Geriatr Gerontol Int 2023; 23: 289–296. [ABSTRACT FROM AUTHOR]

Driven by deep learning, great breakthroughs had been made in the field of target detection. Small target detection algorithms were widely used in industry, agriculture and other fields. But the small target had few available features and the loss of small target detail information in feature extraction. So it led to the low accuracy of the small target detection algorithms. In this paper, we proposed DBF‐YOLO algorithm based on the classical YOLOV5. The classical YOLOV5 algorithm with high speed. The detection speed of the minimum model could reach 24 ms. However, the deep network structure led to the low detection accuracy of small targets. Our proposed DBF‐YOLO algorithm was an improvement on the problem of small target information being lost. The main contributions of this article were mainly: First, a shallow feature extraction network was introduced in P1 layer, more details of small targets could be well retained. Second, by adding the feature fusion network of shallow feature map and the detection output part in the FPN + PAN layers, the algorithm's accuracy and generalization ability were significantly enhanced. Compared to YOLOV5, the performance of the DBF‐YOLO algorithm was significantly improved. On the validation set, mAP@0.5 and mAP@0.5:0.95 were increased by 8.80 and 5.90%, respectively. Recall was increased from the initial 34.50–41.80%. Precision was increased from initial 44.20 to 50.70%. On the test set, mAP@0.5 and mAP@0.5:0.95 were increased by 6.40 and 3.90%, respectively. Recall was increased 5.10%. Precision was increased 6.60%. Experiments had shown that the improved algorithm achieved good results in accuracy. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The auxiliary resonant snubber‐based converter (ARSC) has the advantages of low dead‐time effect and low switching loss. However, the auxiliary switches suffer from high reverse recovery loss and high reverse recovery current in high‐switching frequency application. Thus, the ARSC with saturable inductor is proposed to solve the problem above. In this paper, the operating principle of ARSC with saturable inductor is analyzed, and the duty cycle operating range that can realize ZVS in the full load range is deduced. The reverse recovery model of the auxiliary switching device body diode is established to analyze the circuit parameters' influence. Then, the influence of the saturable inductor on the reverse recovery peak current and reverse recovery loss is analyzed. Based on the analysis results, the saturable inductance parameters are designed. Finally, based on the experimental platform of the ARSC, the effectiveness of the proposed method is verified. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Abstract in order to study the torque ripple of permanent magnet synchronous motor for electric vehicle, the method of modular poles instead of single pole is adopted to reduce the torque ripple. The modular poles consist of three kinds of permanent magnets with different remanence and are arranged in a sinusoidal distribution. The pole arc length and position of each magnetic pole are calculated according to the cutting area of sinusoidal air gap flux density wave. By changing the cutting area of sinusoidal air gap flux density wave, the optimal pole arc coefficient of each permanent magnet was determined, and the magnet pole combination with the smallest torque ripple value is obtained. The results show that the sine degree of back electromotive force is improved obviously, the cogging torque is decreased greatly, and the motor with modular poles has obvious effect on torque ripple suppression. The torque of the motor with different kinds of magnetic pole combination is more stable than that of the motor with the same kind of magnetic pole combination. In this paper, the method of using modular poles instead of single pole to reduce torque ripple is of positive significance, which provides a reference for the subsequent performance optimization of electric vehicle motor. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, we investigate power adjustment for multi‐agent systems in a wireless network where communication range is limited. The approach in which communication range is dynamically changed is utilized so as to save power consumption. However, since drawback of this approach is that agents cannot expand their communication range, it causes that communication between agents tends to be disconnected. To overcome this problem, we propose two power adjustment methods. In the first method, communication range is temporarily expanded in accordance with the number of neighboring agents. In the second method, agents change their communication range by using information on the total number of agents and relative distance between an agent and the farthest neighboring agent. Through numerical simulation, we show that the proposed power adjustment methods reduce power consumption and improve success rate for consensus. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A novel sliding mode observer for speed estimation in sensorless induction motor drives at zero and low speed is proposed in this paper. First, aiming at the poor stability when the induction motor runs at low speed, analyze the reasons of the poor stability and a new feedback gains design method is proposed. Second, for the problem of ignored flux error in speed estimation which cause speed error at low speed, a new compensation method is put forward, which can improve the accuracy of speed estimation in the dynamic and steady state of the system. Meanwhile, a continuous function is given which can replace sign, to restrain the chattering problem of sliding mode observer. Detailed simulation results are given showing the operation at zero and low speed, the results prove the effectiveness of the proposed sliding mode observer. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

To further improve the control accuracy of the magnetic field generated by particle accelerator electromagnets, it is necessary to model not only the magnetic hysteresis behavior but also the magnetic after effect, which has never been studied in the previous literature. In this paper, the gap magnetic field of an accelerator magnet was measured under various excitation conditions to acquire the experimental data required for modeling. Consequently, it was clarified that the magnetic after effect may influence the magnetic hysteresis behavior. Moreover, it was accordingly indicated that a novel modeling technique is required in addition to the conventional hysteresis models developed in the electric machine field. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, a novel doubly salient PM motor based on parallel path magnetic technology (PPMT) is presented. PPMT is an advanced magnetic control technology, which can be applied to linear and rotary actuators. First, the fundamental principle of the PPMT prototype is elaborated, and then a comprehensive research and analysis of PPMT motor is carried out, with particular emphasis on machine topology, operation principle and electromagnetic performance. The equivalent no‐load PM magnetic circuit model is established and equations for calculating the main PM flux are derived. Besides, a dual‐stator 6‐pole PPMT motor prototype has been developed to valid the analysis. According to the similarity of topology and operation principle, comparison between the FSPM machine and PPMT machine is conducted, which leads to the conclusion that the PPMT motor has lower cogging torque, lower torque ripple and better sine back EMF waveform, the PPMT motor is more suitable for servo applications compared to FSPM motor. Finally, to improve the power density of PPMT motor, FE parametric modeling method for designing the three coupled stator parameters, which are the PM width, the stator yoke width and the second airgap length is given out. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Electric field distribution is a determinant factor of air gap breakdown voltage. This paper defined an effective electric field zone between the sphere gaps for feature extraction, and 29 parameters were extracted from this zone to reflect the electric field distribution. A data mining model was established by back propagation neural network (BPNN) for sphere gap breakdown voltage prediction, taking the electric field features as inputs. The maximum information coefficient (MIC) method was used to select features strongly correlated to the breakdown voltage, and a multi‐strategy improved salp swarm algorithm (ISSA) was applied to optimize the BPNN parameters to enhance the prediction performance. The standard sphere gaps provided in IEC 60052 were taken as training set and test set, which were divided according to the electric field nonuniform coefficients. The breakdown voltage prediction results of test sample sphere gaps demonstrate good agreements with the experimental values. With input features selected by the MIC method, the ISSA optimized BPNN model has a mean absolute percentage error of only 0.83% and a maximum relative error of 5.86%. By constructing the nonlinear mapping relationship between the effective electric field features and the insulation strength, this study provides a new approach to predict air gap breakdown voltage. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents the importance of the visual expression of factor decomposition in regression analysis, which is particularly worthwhile for undergraduate students whose majors are not mathematics but social science. The conventional purpose of regression analysis is to examine specific hypotheses empirically. In particular, the statistical significance of the explanatory variable was tested, which may have been difficult for many students to understand mathematically. To remedy this, factor decomposition is introduced in the same way that human body composition is broken down into water, fat, and muscle. As an illustrative example, multiple regression was applied to the determinants of housing rents in Japan. The explanatory variables were the living area, building age, and walking time from the nearest station. The findings suggest that, with the help of visual expression, a student can easily appreciate which variable significantly affects housing rents. [ABSTRACT FROM AUTHOR]

Contextual entrepreneurship and mixed embeddedness approach alike emphasize the importance of the political‐institutional embeddedness next to social embeddedness along with further contexts for migrant entrepreneurship, yet the aspect of international migration policies as an important institutional framework has been somewhat neglected. This paper introduces the case of political‐institutional embeddedness of migrant entrepreneurship in Japan from an international migration policy perspective, discussing embeddedness of migrant entrepreneurs and their support institutions from a multi‐scalar perspective. By analysing the migration policy context of migrant entrepreneurship at different policy levels, that is, national, regional and urban scales, it demonstrates the analytical value of differentiating policies along these scales and also their inter‐connectedness, conceptually proposing the inter‐ and trans‐scalarity of these policy contexts. By bringing issues of migration regimes and particularly the East Asian developmental state as a lens to analyse migrant entrepreneurship, it brings further approaches in comparatively analysing different entrepreneurial contexts for future research. [ABSTRACT FROM AUTHOR]

The 1974 trade act substantially increased the executive branch's authority in trade negotiations through the granting of fast‐track and Section 301 authority. This paper evaluates the effect on U.S. voting behavior resulting from trade with Japan over 1976–1992 time period. To capture U.S. trade exposures to Japan, we develop the Bartik index from Autor et al. (2013) for import competition with Japan and show that local exposure to import competition had statistically significant negative impacts on Republican presidential candidates over the 1976–1984 period. Although the second Reagan administration used Section 301 to open Japan's markets and Japanese firms shifted production to the United States, job‐creation effects of exports and foreign direct investment did not have any influence on voting outcomes. [ABSTRACT FROM AUTHOR]

The importance of involving citizens in the early stages of public sector innovation and bottom‐up governance arrangements for collaboration has been proposed in a number of theoretical papers. However, to date, few empirical studies are evident in the literature. To deepen our understanding of collaborative public sector innovation, our exploratory article analyses: (i) the actors of collaboration, (ii) collaboration across the innovation stages, (iii) the perceived aspects of collaboration for innovative outcomes, and (iv) the governance of collaboration. Our analysis covers 99 innovations from Italy, Japan, and Turkey. We reveal that collaboration still largely occurs within the bureaucracy of public sector organizations. Attempts to include civic and private sectors are evident, depending on the country context. Further, we uncover that a mutual understanding and shared goals are crucial for success, which is accomplished through top‐down governance as opposed to self‐governed bottom‐up networks. [ABSTRACT FROM AUTHOR]

Japanese farms currently occur on a small but expanding average physical scale and annual sales, in a decreasing and aging labor force, increasingly abandoned farmland and massive access of corporations powerful in capital and management. The government has proposed to accelerate agricultural growth through adopting high‐level smart technologies in large‐scale farms, with a series of favorite policies and measures. This paper reviews the connotations, characteristics and technologies of smart agriculture in the views of Japanese scholars, the practice of smart agriculture in Japan, followed by a case study on the smart rice production model 'NoshoNavi1000'. The results show that Japanese scholars have conducted in‐depth and massive studies in smart agriculture, with regional characteristics in the orientations on labor‐saving, precise management, disaster reduction and inheriting traditional farming skills. The government's ambitious objective is supported by its all‐round policy package, including project demonstration, supporting services, environmental improvement, education and training, and overseas outreaching. Closely combined with the planting structure of Japanese agriculture, rice production is an important sector for the R&D and application of smart farming in the form of either individual technologies or models. The policies and technologies have achieved benefits in saving labor and production costs, and improving the profit margin. Through years of on‐farm application, 'NoshoNavi1000' has been developed to involve the major technological components of smart agriculture. It has contributed to improving rice yield, production efficiency and profitability of large‐scale farms, through real‐time data collection, comprehensive and professional data mining, and specific and practical feedbacks. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In recent years, the aggregation business has gained a lot of attention in Japan. Aggregators will make contracts with customers with photovoltaic (PV) power systems and battery energy storage systems (BESSs) including electric vehicles (EVs) to participate in electricity markets. Aggregators might have to pay electricity supply‐demand imbalance charges when generated and consumed energies contracted at the day‐ahead supply‐demand market are different from those at the current day operation due to distribution network constraints such as voltage and power flow limitations. Therefore, the information on network constraints is very important for aggregators to determine their day‐ahead schedules. In this paper, we evaluated the relationship between aggregator supply‐demand schedules and the distribution system operation. It was assumed that the reverse power flow limitations due to network constraints are notified to the aggregators by distribution system operator (DSO). Two cases of the aggregators' schedules of PV systems and stationary BESSs were compared in the simulations. In addition, aggregator strategies for making adequate schedules were evaluated. [ABSTRACT FROM AUTHOR]

With the continuous increase of solar penetration rate, the volatility and randomness of solar irradiance have brought difficulties to grid management. Therefore, accurate characterization and maximum power point prediction of photovoltaic (PV) modules is important for maximum power point tracking and ensuring grid stability. The single‐diode model is that traditional characterization method commonly used but is inconvenient and complex because it employs an implicit equation. This paper proposes a novel model, based on an artificial neural network (ANN) with 4‐input and an explicit analytical model, for estimating the maximum power point and current–voltage (I–V) characteristics of PV modules under different operating conditions. Based on irradiance and temperature, the model considers the solar zenith angle and the solar azimuth angle, reducing the loss of accuracy of the solar spectrum and the solar incident angle. The input layer of the neural network has four neurons, which are solar radiation, module temperature, zenith and azimuth. The outputs are the four shape parameters in the explicit analytical model. Once the neural network is trained using historical measured data, it can build a shape model based on the temperature, solar radiation, zenith angle and azimuth angle at a certain moment, and estimate the maximum power point and I–V characteristics without solving any nonlinearity formula equation. Through experimental verification, it can be concluded that the 4‐input neural network after increasing the zenith angle and the azimuth angle is more accurate than the 2‐input neural network. Finally, the experimental data of four types of photovoltaic modules are used to verify the reliability and accuracy of the proposed model. Since the zenith angle and azimuth angle are considered, the accuracy of the model is improved and the calculation time is reduced. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

By virtue of a great progress of semiconductor fabrication technologies, micro electro‐mechanical systems (MEMS) have been developed for a wide variety of industries. For reliability of MEMS, micromaterials in MEMS need to be examined experimentally, and the obtained results need to be reflected in the design of MEMS. In addition, with the benefit of such the MEMS technology, nowadays mechanical characteristics of nanomaterials have been evaluated precisely. Nanoscale mechanical testing provides an opportunity to find new unique physical phenomena, such as plastic deformation in Si at intermediate temperatures. In this review paper, mechanical testing technologies developed for investigating micro and nanoscale materials are reviewed. Then, mechanical characteristics of Si and other materials evaluated using the micro and nano mechanical testing technologies are introduced. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Ice accretion on transmission lines seriously threaten the stable operation of power grid. The current research focuses on the discharge development and flashover characteristics of ice‐covered insulator. Due to the irregular structure of the insulator, very few studies concentrate on the mechanism of ice accumulation. In the present study, the local collision coefficient was determined, and then a three‐dimensional numerical model for rime ice deposit accumulation on polymeric insulator was established based on computational fluid dynamics and verified by experiments. Results show that the local collision efficiency decreases along the rod and the edge of the shed from the front stagnation point to both sides, whose maximum values are 0.73 and 0.74 in the research scope. Rime ice amount on the insulator increases with the increment of environmental parameters including wind velocity, liquid water content, and median volume diameter of water droplet. It was proved by numerical simulation and artificial tests that the position with a high collision efficiency is heavily covered with rime ice. Through comparison and analysis, the numerical model can well simulate the process of rime ice accretion on polymeric insulator, and the relative error of ice amount between calculated by the model and that obtained by the test is less than 18.8%. The research in this paper realizes the visualization of rime ice‐coating process of polymeric insulator. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Energy‐efficient train operation (EETO) in high‐speed railways (HSRs) is an extra cost‐effective and flexible means to promote energy‐saving. This paper first examines the energy consumption sources and energy‐saving measures of high‐speed trains (HSTs). Then presents the EETO in HSRs, including three categories: energy‐efficient train control, energy‐efficient train timetabling, and EETO considering train timetabling and driving strategy. Next, the current research status and progress on three aspects of EETO in HSRs, namely optimization algorithm, constraint condition, and oriented scenario, are sorted out. Finally, the research on EETO in HSRs has prospected and proposed directions that can study in depth in the future. By summarizing and reviewing the research on EETO in HSRs, it is hoped to furnish a reference for the railway sector to enhance quality, efficiency, and green, low‐carbon development. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Model predictive control has been wildly used in the modern power electronic converter with the advantages of the multi‐objective optimization, no additional modulator is required and small grid current harmonic. However, the switching operation is not constant and higher sampling frequency must be required. A novel direct power control using model predictive control (DPC‐MPC) strategy is presented in this paper, which achieve the optimal vector prediction scheme with constant switching frequency operation. The calculation process is greatly simplified due to the optimal voltage vector generated directly, then, it applied to the control of a three‐phase three‐level T‐type grid converter. A cost function is first built to balance the neutral‐point‐potential voltage. After then, the cost function is updated by considering the delay caused by the calculation, sampling and gate driver. Finally, a comprehensive comparative study with the conventional DPC‐MPC strategy is introduced to verify the superiority of the presented DPC‐MPC. The simulation and experimental results show that the steady and the transient performance of the grid current with the proposed DPC‐MPC control strategy are effectively improved. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Japan's fine ceramics (advanced ceramics) industry, which reached US$30 billion of production in 2018 (an annual growth rate of 6.3%), accounts for 40% of the global market. The mission of the Japan Fine Ceramics Association (JFCA), which consists of 116 corporate members related to fine ceramics, is to further promote the development of this industry. In this paper, we describe the recent trends of fine ceramics industry and the latest JFCA's activities, including the publication of the FC Roadmap 2050 (2021 edition). This roadmap addresses fine ceramics technologies and products that will meet increasingly diverse needs of society, market, and industry in the year 2050. [ABSTRACT FROM AUTHOR]

Train communication network (TCN) is an important guarantee for the reliable and safe operation of high‐speed rail train. The higher reliability of the TCN is, the safer operation of high‐speed rail train will be, and the cost of overhaul and maintenance will be greatly reduced. The 250 km/h high‐speed rail TCN being developed in China is the first time that the train communication Ethernet (TCE) is used as train control network. Therefore, it is of great practical significance to analyze the reliability of TCE and improve the reliability of TCN design and vehicle design. Dynamic fault tree (DFT) and fault Petri nets (FPN) are both important methods for system reliability analysis. Among them, DFT is most widely used in the field of engineering analysis. The FPN method also has its unique characteristics and advantages, which can describe fault propagation analysis and dynamic transition process in practical application. In this paper, TCE's structure, working principle, and fault mode are analyzed to sort out the relationship between complex fault events and establish a DFT with TCE failure as the top event. DFT and FPN methods were combined to better express the dynamic propagation of TCE fault and carry out the fault probability evaluation and system reliability based on the known prior failure rate. The analysis results show that improving the reliability of specified network segments of TCE is of great help to improve the reliability of the high‐speed rail train. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A local immunization strategy, which is effective in huge no‐scale network, is proposed in the paper. When there is an outbreak of virus in network, vaccinating limit nodes can reduce the damage of virus by preventing the propagation. Immunization strategy, which has been a hot topic for years, manages to choose the proper nodes to vaccinate. However, with the modern network growing large rapidly, the classic immunization strategies, such as degree‐based strategies and betweenness‐based strategies, will face the efficiency problem and accuracy problem. To solve the problem, we have pro‐posed a local immunization strategy, which performs effectively in huge no‐scale network. Firstly, we train an unsupervised graph neural network to get the embedding of nodes. Then with the help of node's embedding, we find the nodes exposed to virus spreader most severely and choose them as the vaccinated target. The calculation of node's exposure is local and fast, and it can depict the node's suspicious exposure to the virus from the global view of the network, which makes our immunization strategy approximate the global optimal solution. In addition, the vaccinating targets are calculated timely according to real‐time distribution of virus spreaders, by this way, our strategy is adaptive to the fast changes in the propagation of virus. At last, we refine the time complexity to make our strategy practical in huge network. Compared with current method, our network immunization strategy shows privilege in the simulation experiment. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a single‐stage DC/AC converter for the implementation of a high‐power‐density onboard AC inverter. The proposed circuit integrates a non‐isolated DC/AC converter into an isolated DC/DC converter using only simple duty control and phase‐shift modulation, which reduces the required number of semiconductor switches. Additionally, a coupling inductor and center‐tapped transformer can be shared by the two converter functions, so they can be integrated without additional circuit components. This paper describes the operating principles of the proposed converter and design solutions are extracted using multi‐objective optimization to achieve optimal performance in terms of power density and efficiency. Based on the design solution extracted through optimization, a prototype with a volume of 0.5 l was fabricated and a power density of 3.0 kW/l with an efficiency of 94.7% was achieved at a rated power of 1.5 kW. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In induction motor no‐load test, the no‐load losses usually include the stator copper loss, iron loss, the friction, and the windage losse, and the stray loss, and the rotor aluminum loss often is ignored. In this paper, a new method that separates the rotor aluminum loss from the no‐load losses is mentioned. Although, in IEEE Standard 112 and IEC34‐2, the rotor aluminum loss is neglected in no‐load test. However, in proposed method, the rotor aluminum loss is considered as an important part of the no‐load loss. Therefore, this paper intends to develop a new testing method to obtain the rotor aluminum loss under no‐load condition. In this case, six induction motors of the same kind (3 kW, four‐poles) are chosen to carry out no‐load and ideal no‐load tests. Through the comparative analysis of experimental data, the no‐load rotor aluminum loss accounts for about 13.4% of the no‐load loss, and the test approach can also explain that this part loss is not generated by higher harmonics. Based on these results, this paper demonstrates that the rotor contact resistance has great influence for the no‐load rotor aluminum loss, and a rotor resistance analysis model with rotor contact resistance is proposed. Final, the proposed method offers the possibility of taking measures on rotor resistance to improve motor efficiency. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper introduces the concept of intermittently connected sensor networks where sensors are sleep most of time and become active randomly and rarely. In the networks, packet collision probability and power consumption can be reduced. Meanwhile, the delivery delay increases with the use of the low activation values. In this paper, we design the energy‐efficient intermittently connected sensor networks, considering this trade‐off of activation control. We first provide the algorithm that computes the optimal packet forwarding rule achieving the minimum delivery delay, which can be calculated using the activation rates. We then propose the activation rate control methods, which control the activation rates of the sensors based on the density of the sensors and/or the number of wake‐ups of sensors having relay packets. By doing this, we can improve the delay performance, while suppressing the increase in the packet collision probability and the power consumption of sensors. Through simulation experiments, we demonstrate the effectiveness of our activation control methods in the intermittently connected sensor networks. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Machine learning (ML) has become a rising sophisticated technological application trend in the electrical industry in recent years. Such innovation provides optional methodologies for many existing applications, such as power and load profile forecasting, reliability evaluation, substation behavior detection and state observation of electrical equipment, and so on. This paper presents a review of various supervised and unsupervised ML techniques and applications for electrical power systems, including generation, transmission, distribution and micro‐grid. The algorithms and applications are mainly summarized from IEEE journals and the interest of this paper shows the roles and developments of most used algorithms and its corresponding extensions and performance in different applications. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Tracking paleoenvironmental change and past event deposits is very important to evaluate the natural hazard spatially. This paper presents how the environment changes and implies the event deposit depending on the diatom assemblage change. To investigate paleoenvironmental change and identify the difference between tsunami and typhoon deposits, we analyze diatoms from the sediments in two coastal lakes in southern Japan where flood deposits have been linked to historical typhoon and tsunami events (Lakes Kawahara and Ryuo). The sediment cores extend from B.C.E. 500 to approximately C.E. 1000 and the downcore variation in diatom assemblages indicates a series of transitions from saline to fresher conditions in both Lake Kawahara and Lake Ryuo between approximately C.E. 500 and 1700. We observe an obvious deviation in diatom assemblages in event deposits previously identified to be either of tsunami or typhoon in origin. For the most prominent event deposit preserved in Lake Ryuo by the Hoei tsunami of C.E. 1707, the deposition of marine diatoms serves as evidence of marine flooding, while the subsequent deposition of soil and freshwater diatoms indicates the mobilization of terrigenous sediment during returning seaward flows. In contrast, the most prominent event deposit in Lake Kawahara is associated with freshwater flooding by the Kamikaze typhoon of C.E. 1281 and contains very low diatom abundances and a peak of freshwater taxa, followed by a peak in diatom counts potentially due to greater biological activity induced by a resultant influx of nutrients and re‐oxygenation during the event. [ABSTRACT FROM AUTHOR]

The rapid growth of electricity demands for recent years leads to many global concerns, including greenhouse, energy risk, and large size brownouts, which require modern energy management system to provide environmental‐friendly power supply service with less cost and higher reliability. However, most of previous studies separately focus on improving prediction accuracy or reducing cost and emission of power supply solution by dispatch optimization. To exploit the benefits of microgrid system furthermore, this paper firstly proposes a comprehensive day‐ahead multi‐objective microgrid optimization framework that combines forecasting technology, demand side management (DSM) with economic and environmental dispatch (EED) together. Then, two versions of particle swarm optimization are implemented for obtaining load control plan from DSM model and power supply plan from EED model, respectively. Moreover, two different microgrids' applied scenarios are simulated with detailed sensitivities analysis on key parameters. Experiment results demonstrate effectiveness of the proposed framework, which can obtain load demands profile with better reliability, as well as power supply solution with less cost and lower emission. Meanwhile, beneficial decision supports are provided to manager for their references. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel multi‐objective topology optimization with response surface approximation interpolating various topologies, which is derived by deep learning with training data in the actual design space. The response surface is constructed by means of autoencoder with the training data of geometrically diverse shapes of targeted devices, which can express the interpolations that combine the multiple characteristic structures. The global topology search is performed based on the gradient information of the response surface, by which we can obtain the initial shapes for level set optimization to efficiently obtain easily manufactured and excellent Pareto optimal solutions. The effectiveness of the proposed method is demonstrated by optimizing multi‐flux barriers in a synchronous reluctance motor for the objective functions of average torque and torque ripple. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a novel deadbeat predictive torque control (DPTC) scheme to minimize the torque ripple of switched reluctance motor (SRM) drives. The proposed DPTC consists of torque inverse model and flux‐linkage controller. The torque inverse model is used to realize the nonlinear mapping from the desired torque to the flux‐linkage. On this basis, the flux‐linkage controller predicts the required voltage for a given reference torque at each digital time step. Besides, an improved pulse width modulation (PWM) control is developed to offset the losses caused by power converter and winding resistance. And the digital delay in the actual implementation of the proposed DPTC algorithm is compensated through the estimation + prediction technology. Both simulation and experimental testing are carried out to verify the effectiveness of the proposed control scheme. The results show that the proposed DPTC method has better torque ripple suppression performance than the conventional direct torque control (DTC) scheme. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Heave motion of ships is a complex nonlinear dynamic process and cannot be accurately forecasted using a single prediction model. In this paper, an effective combined forecasting method is proposed to perform ship's heave motion prediction. The proposed method combines back propagation neural network (BPNN), autoregressive model (AR) and extreme learning machine (ELM) through an induced ordered weighted averaging (IOWA) operator. The prediction accuracy is selected as the induced variable and the prediction results are sorted according to prediction accuracy and IOWA operator assigns larger weights to the position with the smallest prediction error. The optimal weights are determined by maximizing the B‐mode relational degree. Experimental results demonstrate its effectiveness of the proposed method. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a deep neural network (DNN)‐based model to recognize fishing vessels. In Taiwan, the vast majority of small fishing vessels are not equipped with an automatic identification system (AIS). As a consequence, the staff in a fishing port administration become heavily loaded when monitoring and managing the fishing vessels accessing a port. The workload is expected to be eased using this work. For the first time in the literature, a captured fishing vessel image was converted to a 128‐dimensional embedding for recognition purposes. The presented model gave a false positive rate (FPR) as low as 1.13% and an accuracy up to 99.47% at threshold = 0.772379. Finally, all the performance metrics, namely, the true positive rate (TPR), the FPR, precision and accuracy, are actually functions of the threshold which can be specified by users to meet specific requirements. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to fill the blank of practical engineering application of inductive control in ozonizer power supply, this paper probes into a scheme of high frequency and high voltage inverter for the control, and analyses operation modes to form a reasonable theoretical result, and introduces a new current zero crossing and phase locking method to adjust the address deviation and ensure that the address pointer directs to the last value of inverter current by changing the sampling period and adjusting the error of practical reference address pointer at each zero crossing point. The results from theoretical derivation, numerical simulation, and power experiment prove that the scheme can suppress the current spike caused by diode reverse recovery and reduce the power loss of switch devices, which is conducive to cost reduction. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

For the power system integrated with the doubly‐fed induction generators (DFIGs), the frequency regulation may be provided by the DFIGs in addition to the synchronous generators (SGs). With the model predictive control (MPC), the active power output of the DFIG is adjusted by predicting the system frequency with the dynamic power flow (DPF) algorithm. In this paper, the governor delay of the SGs is included to improve the accuracy of the DPF‐based prediction model. The DPF predicts the frequency response with the desired active power response of the DFIG. To reach the reference with the high accuracy and efficiency, the MPC‐based direct rotor current control is applied to adjust the active power output in coordination with the frequency regulation, forming the proposed hierarchical frequency control strategy. The mechanical transient of the DFIGs involving the shaft and pitch angle system is included in the DPF model to introduce the mechanical constraints of the DFIGs to the MPC. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Accurate assessment of lightning protection performance of extra high voltage transmission lines is important for transmission line design and different lightning protection. Based on the electro‐geometrical model, this paper introduces the angle influence factor, and presents an algorithm for shielding failure trip‐out rate of angle tower, and the existing algorithm is expanded. By establishing the three‐dimensional geometric model of the angle tower, the electrical geometric relations of conductors and ground wires on both sides are analyzed, respectively, and the projection area algorithm for shielding failure is modified. To further verify the application value of the calculation algorithm, the change of the shielding failure trip‐out rate of the typical angle tower with the bending angle of transmission line and the tower height in a 500 kV transmission line is analyzed. The analysis results show that the trip‐out rate of the outside corner is higher than that of the inside one, and with the increase of the angle and the height of the tower, the trip‐out rate shows an upward trend. When the tension tower height is 71.5 m and the angle increases from 0° to 80°, the outside shielding failure trip‐out rate increased by 10.9% and the inside decreased by 9.3%. Compared with the classical electro‐geometrical model calculation, the difference of trip‐out rate is 4.3% when the bending angle is 80°. When the tangent tower height is 70 m and the angle increases from 0° to 40°, the shielding failure trip‐out rate on the outside increased by 5.9% while the inside decreased by 6.2%. The research results provide a simple algorithm for solving bending transmission line and give some reference for lightning protection design of EHV transmission lines. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]