Structure-durability mechanism of Three-Way-Catalyst (TWC) particles membrane filter was investigated through TEM images of contact areas between two agglomerated TWC particles. After those agglomerated TWC particles were sintered at 700, 800, 900 and 1100℃, a thin sample around the contact area was cut off out using an FIB-SEM system. From the TEM image analysis, the contact area becomes larger by thermal expansion of both TWC particles with temperature. Moreover, nanometer-sized primary particulates such as alumina and ceria-zirconia which are elements of the single TWC particle cross over the apparent contact line between two agglomerated TWC particles. As a result, the percolation structure becomes stronger as the sintering temperature increases because the crossover rate increases.

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Emission regulations for vehicles are continuously being strengthened in various countries. Additionally, the electrification of vehicles leads to lower exhaust gas temperature and limits on board space. To overcome those matters, we have developed a compact and low temperature dependence after treatment system using plasma and HC adsorption. We investigated PN and HC removal performance under cold start condition. As a result, PN removal rate and pressure drop of the plasma reactor were maintained during continuous driving. Ag ion-exchanged BEA indicated high HC adsorption rate of 80%. HC emissions were reduced by 50% from exhaust gas after the three-way catalyst.

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We are developing a “compact water-cooled fuel cell system” that can be used to refuel all types of mobility. The FC stack adopts compact FC separators manufactured using our core precision press technology. The cooling device adopts a “thermal management system” that utilizes the thermal characteristics of the hydrogen tank and the water-cooled FC stack. These technologies have enabled the miniaturization of the entire system.

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Thermal management of the lithium-ion battery in the hybrid and battery electric vehicle, which controls the battery temperature, is important to counteract battery degradation and overheating. In the previous research, we proposed the thermal management system for the battery electric vehicle, where the battery refrigerant and chiller are connected to the long life coolant circuit based on the vehicle system 1D simulation model. In this report, we improved the thermal control performance of this system by modifying the system structure from the battery electric system to the series hybrid electric system. Then, we optimized the thermal and power management control using the optimization method.

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Expanding the commercial use of electric vehicles is crucial for achieving carbon neutrality in the automobile transportation sector. This study conducted questionnaire surveys targeting two groups: general freight transport companies and those already using electric vehicles, to compare their perceptions of electric vehicles and usage practices. The findings identified external factors that could be challenges to the broader adoption of commercial electric vehicles, such as performance of existing electric vehicles, availability of chargers, and concerns by transport companies.

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Electric wheelchairs, unlike cars, do not have dedicated lanes and operate in shared spaces with pedestrians and bicycles, leading to collision accidents. In this study, we propose a method to estimate collision risk by considering the positional relationship between the wheelchair and pedestrians, as well as the state of the pedestrians. The proposed method involves detecting pedestrians using a stereo camera, estimating their distance and speed, and then estimating the collision risk based on the pedestrians' direction and speed of movement.

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For safe autonomous driving, localization is essential. Conventional point cloud matching methods using convergence calculations have the problem of initial position dependency. While methods that predict the vehicle's position as a likelihood distribution reduce initial position dependency, but they have difficulty handling the 3D information of the point cloud. This study proposes a matching method that retains the features of LiDAR point clouds in a pillar structure and converts them into pseudo-images, using deep learning to estimate the vehicle's position as a likelihood distribution. The proposed method aims to achieve more robust localization compared to conventional point cloud matching methods.

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This research examined the differences in pedal-misapplication accidents between passenger and light passenger vehicles. The number of accidents caused by pedal misapplication in passenger vehicles was higher than that in light passenger vehicles. The pedal-misapplication accident ratio, considering traffic exposure effects, was similar between the two vehicle types. Drivers aged 75 and older were more often involved in these accidents across both vehicle types. In single-vehicle accidents caused by pedal misapplication, the proportion of fatal injuries to drivers was similar for the two vehicle types. However, serious and slight injuries were more frequent in light passenger vehicles, indicating a higher risk of injury.

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Automobile electrification requires miniaturization and power saving of cabin air conditioners and battery cooling systems. For further performance improvement, it is important to improve the performance of heat exchanger by effectively using turbulence produced by blower. However, the influence of fan turbulence on fine fins of heat exchanger is not clear. In this study, the effect of flow turbulence on heat transfer of the louver fin was investigated using large-scale LES. As a result, it was found that the separation between louvers was suppressed by the effect of fan turbulence, and the amount of heat radiation increased.

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When wipers are operated while driving, washer fluid flows over side windows, affecting the driver's visibility. To predict this phenomenon, this study introduces a CFD method for analyzing airflow and washer fluid behavior using the Lattice Boltzmann method and the Lagrangian particle tracking. The wind tunnel test validated this method, showing consistent results with the experiment, including the washer fluid spread from the upper to the center of the A-pillar and the position of the washer fluid reaching the side window. This method allows for early-stage design improvements in vehicle performance related to washer fluid, even without an actual vehicle.

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While tailpipe emissions have been significantly reduced by stricter pollutant limits, the proportion of non-exhaust particle emissions such as brake wear has become noticeable. Therefore, introduction of regulations on brake particle emissions in the next European regulation (Euro 7) is currently under discussion. In this study, the measurement system for brake particle emissions has been developed. Validity of the measurement systems and emissions behavior are discussed based on measurement results of brake particle emissions during WLTP-Brake cycles.

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In this study, we focus on improving the performance of raindrop removal. Conventional methods for still images and videos have limited available information, leading to performance constraints. Therefore, we propose a novel approach focusing on camera placement in autonomous driving, utilizing images from other cameras captured at the same time. In the proposed method, the camera images without raindrops are used for raindrop removal by transforming the viewpoint. The proposed method significantly improves the baseline method in terms of subjective evaluation and object detection, and the effectiveness of the proposed method is demonstrated.

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The objective of this study is to improve the decision performance for lane change feasibility by planning trajectories that consider future variations. We propose a method that imposes constraints on the probability of maintaining safe distances from other vehicles in trajectory generation using chance- constrained model predictive control. In merging scenarios where the behavior of other vehicles is highly variable, the success ratio of merging improved by 25.9% and false positive ratio decreased by 30.3%. Additionally, the performance of the proposed method was evaluated by applying it to a real vehicle.

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Based on the system simulations, we showed the effect of the aluminum electrolytic capacitors' low-temperature behavior on the actuator's control in the previous works. We assembled an actuator system that followed the previous system simulation to confirm whether the same phenomena appear in a low-temperature condition. We will show the details of these results.

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This study proposes a novel video analysis technique utilizing multimodal large language models (MLLM) to aid AD/ADAS logic development. By combining rule-based algorithms and MLLM corrections, the precision of lane change detection improved from 0.74 to 0.90. Evaluations using monocular camera footage from Japanese roads revealed that MLLM effectively identified error-prone scenes, aiding logic improvement. However, challenges such as spatial misinterpretations suggest limitations in MLLM's temporal and spatial reasoning. Future work aims to address these issues and expand applications to diverse driving events.

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Although the demand for petroleum products is expected to decrease, diesel fuel is relatively stable. To increase the production of diesel fuel, the ways of blending kerosene and expanding to utilize cracked diesel fuel are used. Since the cracked diesel fuel has high aromatic and naphthenic components, which increase the amount of PM. So, it is necessary to take countermeasures such as lightning of distillation. To identify the impacts of these properties on PM production, the test was conducted using test fuels varying compositions and distillation properties.

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For better understanding and model validation of wall heat loss on diesel engines, high-speed thermography of piston surface impinged by a diesel spray flame was attempted in a top-view optical engine. Infrared radiation from the piston surface was directly visualized through the sapphire window using a high-speed infrared camera. As a result, it was demonstrated that infrared high-speed thermography can be applied to the diesel engine piston surface by suppressing the soot luminosity using oxygen-containing fuel such as Oxymethylene Dimethyl Ethers (OME), simultaneous imaging with a visible camera to distinguish the soot luminosity in the infrared radiation image, and using a bandpass filter to cut off the infrared radiation from the gas components in the cylinder.

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A hydrogen engine was developed by converting the fuel supply system of a mass-produced LPG engine to accommodate hydrogen, with the goal of achieving carbon neutrality for industrial engines. To address the torque reduction caused by the conversion to a hydrogen engine, turbocharger was added, along with abnormal combustion suppression technologies and hydrogen concentration reduction technologies in the crankcase. Minimal system modifications enabled the achievement of power performance comparable to the base engine as well as low NOx emissions.

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It has been necessary to investigate into combustion phenomena and fuel spray characteristics aiming to achieve thermal efficiency improved commercial heavy-duty diesel engines. This study focuses on the simultaneous improvement in cooling loss and indicated thermal efficiency by means of an offset orifice nozzle presented in the former study, and investigates further into combustion and emission characteristics of a high-compression-ratio heavy-duty diesel engine equipped with offset orifice nozzles. Internal nozzle flow analysis by numerical simulation and observation of fuel spray were also carried out to identify the cause of significantly different combustion phenomena.

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We are developing a coil immersion oil-cooled structure to improve e-Axle power density. In this report, we have investigated the effect of the cooling performance improvement by testing a prototype machine. As a result, the following conclusions were obtained. In oil-immersed cooling, the distance between coils can maintain high continuous performance by considering the flow rate of the cooling oil between the coils and the effect of copper loss in the indirect water cooling structure, it was confirmed that the temperature difference from upstream to downstream is small, but in the oil-immersed cooling structure, there is a temperature difference of about 10K between upstream and downstream, and the maximum temperature that determines the continuous torque occurs downstream. In the oil-immersed cooling structure, the sensitivity of the coil temperature to the amount of cooling oil is low upstream and high downstream. In this oil-immersed cooling structure, it was confirmed that the continuous operation area for the maximum torque is about 60%.

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We studied a test method of EV range per charge, which is calculation from the electric energy stored in the battery and the electricity consumption, based on the existing test methods in relation to heavy-duty EVs. We conducted experiments on chassis dynamometers with various driving patterns, and compared candidate methods for calculating EV range per charge. The results demonstrate that a calculation method which uses electricity consumption at fully charged battery and one at sufficiently depleted battery can reflect characteristics of regenerative braking and reduce the time required for HILS test.

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A small delivery electric vehicle (EV) was equipped with a pyranometer and subjected to a long-term demonstration test in Koriyama City, Fukushima Prefecture, during which EV'senergyconsumption and solar irradiance were measured. Based on experimental data, simulation modelsweredeveloped to evaluatethe energy-saving potential associated with the installation of a PV system. Then the impact of the delivery vehicle's distinctive drivingconditions, solar altitude and ambient temperatureto the EV's energy consumption and photovoltaic (PV) power generation was also evaluated.

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This paper describes a fatigue prediction method for the point joints in car bodies. There are two directions of fatigue crack propagation, the sheet thickness direction and the interpolate direction, for the fatigue fracture of point fasteners. It is essential for accurate fatigue life prediction to consider the crack propagation direction using numerical simulations. Previous papers proposed simplified joint models for vehicle bodies' fatigue life prediction that assumed a specific fracture mode. It took a lot of work to simultaneously estimate multiple fracture modes using a particular model. Therefore, they needed to use various models properly or to consider complicated parameter combinations. This paper proposes a fatigue life prediction method considering multiple fracture modes simultaneously. A simplified model representation method is introduced for Flow Drilling Screw joints.

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The authors conducted an experiment to investigate the effect of low-frequency components included in motor vehicle noise on subjective evaluation in a low-frequency sound chamber. Single pass-by noises emitted by heavy vehicles with a predominant sound pressure level in the low-frequency range of 40 Hz or 50 Hz were used as sound stimuli. In this paper, we discussed the influence of the peak sound pressure level in the low-frequency component on the oppressive or vibratory feeling, which is characterized as the effect of low-frequency sound, and on the discomfort feeling due to the noise.

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This study proposed a method for calculating ΔV that considers the rotational behavior of vehicles during side impact accidents and validated its effectiveness through actual accident data and simulations. While ΔV measured on the airbag ECU location is commonly used for assessing impact in traffic accidents, there is an opportunity to enhance the accuracy of impact assessments by incorporating the vehicle's rotational behavior. The study highlighted the variations in ΔV based on collision locations and introduced a method that utilizes acceleration sensor data from the B-pillar and C-pillar to achieve a more precise impact assessment. Simulation results demonstrated a good correlation with the proposed calculation method, indicating the practicality of calculating ΔV while considering rotational behavior. Future research will focus on gathering additional data to further broaden the applicability of this method, paving the way for continued improvement in impact assessment techniques.

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Decarbonization scenarios based on power sources were examined for motor vehicle transport in Hokkaido. If eco-friendly cars continue to increase at the current rate, CO2 emissions will be reduced in the short term due to the effect of HEVs. However, after around 2030, new fossil fuel vehicles will hardly be introduced, but the impact of CO2 emissions from electricity used by EVs and PHEVs will become significant. As a result, CO2 emissions from motor vehicle transport as a whole will increase after 2030. In addition, the transportation methods within Hokkaido with the lowest CO2 emissions, including rail transportation, were identified.

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Recently, carbon fiber sheet molding compound (C-SMC), which is a discontinuous carbon fiber-reinforced polymer composite produced via sheet molding compound methods, has attracted significant interest especially in the automotive industry. The determination of the remaining fatigue life of C-SMC is crucial for ensuring its long-term use. To determine the remaining fatigue life of a material, its fatigue damage degree must be evaluated. In this study, a method for quantitatively evaluating the fatigue damage degree using the non-dimensional thermoelastic temperature amplitude is proposed and applied to C-SMC. This amplitude can be obtained through thermoelastic temperature variation measurements. The experimental results show that, from the early to middle stages of fatigue damage, a decrease in the non-dimensional thermoelastic temperature amplitude can be used to evaluate the fatigue damage degree of C-SMC with an acceptable accuracy. However, in the final stage of fatigue damage, the evaluation error in the fatigue damage degree becomes large. Future studies should clarify the cause of this large evaluation error.

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This study investigates right-turn behavior across oncoming traffic lanes, a maneuver with high accident risk. Vehicle trajectories at a left-hand traffic intersection in Japan were analyzed using drone footage. Based on cognitive psychology, drivers' time perception was incorporated into the analysis. Linear discriminant analysis showed that adding the distance to oncoming vehicles as a feature significantly improved classification accuracy of turn decisions. The results suggest that drivers compare perceived turning time with oncoming vehicle distance to judge timing. These findings may contribute to driver education, right-turn assistance systems, and autonomous vehicle control development.

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With the increasing demands for higher functionality in electronic parts, it is essential to develop design techniques that ensure stable solder joints during the manufacturing process when implementing advanced semiconductors and components on printed circuit boards at high densities. Since fillet lift-off of the solder joints was observed on experimental boards, this paper introduces consideration about lift off phenomena and the robust design method of design parameters by utilizing simulations and AI.

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