Railways are an important transportation mode for land transportation infrastructure, and with the growing interest in global environmental issues and SDGs, the expectation is that related technologies will continue to be developed to facilitate a sustainable society. One of the important research themes in the railway field is energy-saving technology, and the focus of this study is on energy-efficient operation. In the study of energy-efficient operation, data on trains should be measured, however these measurements and experiments are not easy. In this study, an IoT remote system was used to store data in the cloud in real time, so that the data could easily be collected. By analyzing the measurement results, we show that the relationship between operation and energy can be explained by the theory of train operation. Furthermore, in the case of high energy consumption, methods for improvements will be discussed from the theoretical point of view.

This study presents a design method for high-torque-density air-core distributed windings with round wires applied to slotless permanent magnet synchronous motors (SL-PMSMs). The authors extend the conventional method to the case of applying round wires and Halbach-array magnets and clarify the optimization method considering interference with adjacent coils. As a result of the calculation, the objective function, which is the torque constant per square root of the copper loss, is limited to 0.86 times or less relative to the optimal solution. The actual test of a prototype SL-PMSM was conducted to validate the optimization method, and the experimental resistance of one coil is 6% larger than that of calculation, and the objective function measured from the current-torque characteristic at 60kr/min decreased by 30% to that of the calculation.

This paper proposes a direct rotor-phase estimation method for an elliptical voltage injection synchronized with a pulse-width-modulation carrier. A rotor phase has been estimated using a correlation signal that includes phase information. However, traditional methods cannot simultaneously realize robustness against nonideality and estimation performance, because correlation signals they use lack critical information related to the rotor phase. In response to this problem, we identify detailed information and improve the robustness of estimation. The approach directly estimates a rotor phase using signals robust against rotation on current responses, thereby meeting nonideality, and achieves better robustness than that of traditional methods. This paper discusses the way to construct, robustness, and comparison of estimation characteristics between traditional methods and our approach.

Railway operating companies create crew schedules whenever train timetables are revised. These schedules are manually created by experts. However, this manual task is time-consuming because regulatory constraints related to crew schedules must be satisfied. Therefore, we need to develop a crew scheduling support system with an automated algorithm. Herein, we propose an automated crew scheduling algorithm based on mathematical optimization for minimizing the required number of crew members. The proposed algorithm comprises two important steps. First, a set of crew duties is generated, and second, a set of crew rosters is generated to satisfy practical constraints. The computational results based on actual railway line data confirm that the proposed algorithm can effectively minimizing the required number of crew members and reducing the computational time.

Flux-based phase-manipulated damping control is proposed in this study. The proposed method controls damping factor by maniplulating phase based on a flux fluctuation in the flux vector. The proposed method is experimentally verified using an electric-vehicle motor. Moreover, the proposed method improves voltage usage at high speed by suppressing vibration due to motor resonance near voltage limit.

In this paper, we propose a compensation method for systems with a time-varying delay based on model predictive control (MPC). The objective is to improve the path tracking performance while compensating for varying time delay and disturbance. MPC predicts the plant state and sends it to the local predictor to suppress the increase in model error due to time delay. Additionally, the Kalman filter-based disturbance observer improves the responsiveness to disturbances. Experimental results show improved path tracking performance using the proposed method.

Controlling bulldozers at construction sites requires advanced skills. However, training skilled operators is time consuming and expensive. Additionally, the shortage of young workers is problematic. To address these issues, automation of construction machines using artificial intelligence has been studied, which has yielded positive results. Furthermore, using data collected from construction sites, reducing learning time and improving work accuracy is possible. Therefore, in this paper, we propose a path planning method for heavy equipment using offline reinforcement learning, leveraging existing datasets.

In this paper, the offset control of traffic signals is considered. An offset which is the target of signal control parameters in this study, is difficult to optimize owing to its variety of combinations. A traffic signal is controlled using three parameters, namely cycle, split and offset, and these parameters should be determined based on traffic conditions. The offset-optimalization is searched using a genetic algorithm (GA), which evaluates the average travel time calculated by the traffic simulator, and repeats generations to leave superiority individuals. The aim is to eliminate the search time, which has been a subject of previous research. When we propose an initial individual generation method for the GA and examined its effects, it is confirmed that it contributed to shortening the processing time.

The axial gap structure of a half-wave rectified variable field flux motor (AG-HVFM) has been proposed, which has a double stator structure and field winding short-circuited by a diode. Although the AG-HVFM can achieve a high efficiency drive in wide speed and torque range via variable field flux control, its structure deteriorates the average torque and torque ripple. In this paper, we sequentially design the core shape, aspect ratio and current control method for an AG-HVFM to improve its torque characteristics.

Automatic operation of rail vehicles is required to address the future decrease in railroad workers. However, rail vehicles have control difficulties that hinder automatic operation. Therefore, precise control technology is required for automatic operation. In this paper, we introduce a scaled roller rig that simulates the frictional propulsion of a rail vehicle in a scaled-down form to test the control technology. The device reproduces the pressing force between the wheel and rail with the thrust of a linear motor and can be changed at high speed, thereby simulating the variation of maximum friction force in a reproducible manner and contributing to the study of control technology. Moreover, measurements of the relationship between slip speed and friction force were made on a proposed small roller rig device. Consequently, adhesion characteristics similar to those of actual rail vehicles could be obtained.

This paper proposes an implementation and design method of a high-frequency and high-power inverter for wireless power transfer systems. The implementation and design of circuits operated in the megahertz range are complex because the influence of parasitic components on the device and printed circuit board increases in this range. In addition, heat dissipation over an output range of a few kilowatts is still difficult particularly in megahertz operation because of the use of surface-mounted devices in megahertz operated circuits. The design flow and implementation method to achieve megahertz operation over a range of a few kilowatts were validated using theoretical derivation and simulation. Furthermore, the relationship between the thermal structure and soft switching condition was evaluated by measuring of the parasitic capacitance. The experimental results showed that the inverter was continuously operated with a 2.7kW prototype at 6.78MHz.

A method for banknote identification has been developed. As a prerequisite for this process, an ATM stores records captured from accepted banknotes, including customer's information for identification. The proposed method is implemented when a counterfeit banknote is detected. The ATM identifies a record corresponding to the counterfeit banknote among the stored records, assisting in the identification of the customer who used it. This identification is carried out by exploiting characteristic differences between counterfeit and genuine banknotes. These differences are defined in terms of positions and magnitudes of variations. An experiment using simulated banknotes was conducted to assess the effectiveness of the proposed method. Additionally, another experiment involving digitally synthesized banknotes was conducted to determine the performance limits of the proposed method.

This paper presents a semi-open-loop control for a single-phase grid-tied inverter with voltage control. To improve the output current distortion, a disturbance observer, including an inductance value greater than the grid-tied inductance, is applied to semi-open-loop control. Using the proposed method, the inverter output current total harmonic distortion (THD) is reduced by 76% with the grid-connected operation compared to the open-loop control. Moreover, the THD of the inverter output voltage is reduced by up to 57% with the stand-alone operation for a diode rectifier load.

Lithium-ion batteries (LIBs) in electric vehicles at low temperatures must be properly heated to avoid a decrease in their discharge capability. Internal ac heating techniques utilizing Joule heat generated by ac current flowing through an internal resistance of LIB have been proposed as an efficient and fast heating method. However, traditional internal ac heating techniques that use triangular and sinusoidal waves are not ideal due to their relatively low rms value at a given peak current, which results in a long heating time. This paper proposes a 3-level flying capacitor inverter for reducing heating time. The proposed PWM technique generates trapezoidal wave with a high rms value at a given peak current. Experimental results of a prototype for a 12-cell LIB demonstrated that the proposed trapezoidal wave heating reduced heating time to approximately one-third compared with traditional sinusoidal-wave heating.