International Journal of Automotive Technology

In this study, the discrete adjoint approach with the grid deformation technique based on radial basis function was presented to solve the tough problem that the complex shape of the defrosting duct is very difficult to be optimized with multiple parameters in the improvement of the defrosting performance of vehicle. Firstly, the defrosting performance of a light truck was analyzed. Then the discrete adjoint approach was applied by taking the average Nusselt-number as the objective function. The normal surface sensitivity was used in the deformation of the defrosting duct. After 10 optimization cycles, the optimal model was acquired. The results show that, after optimization, the sum of the average Nusselt-number is increased from 3164.16 to 3350.54, which has a positive effect on improving the convection and heat transfer capacity on the windshield effectively. Compared with the initial model, the airflow of the outlet near the windshield is increased from 95.07 g/s to 96.94 g/s, the defrosting time required by the optimal model is reduced by more than 20s. Therefore, the discrete adjoint approach can optimize the complex shape of defrosting duct with multiple parameters effectively, which provides an effective method in the study of automobile defrosting performance.

Uncontrolled expansion of combustion wave in spark ignited internal combustion engine causes knock effect which seriously degrades efficiency and lifetime of the engine. Thus, accurate knock detection and control are essential for obtaining a desired performance from the engine. Usually, knock sensor is used to detect this phenomenon but it has limited accuracy especially at engine high-speed rotations because of natural vibration and external noises. In this study an effective method based on Non-Local Mean (NLM) algorithm has been proposed to improve the knock detection accuracy. This method is evaluated based on four different indicators and four engine cylinders. The results show 52.9 % improvement in knock detection. Also feasibility of real time execution of this method based on embedded hardware has been studied.

The Japan New Car Assessment Program (J-NCAP) evaluates the performance of cars in terms of protection against whiplash injuries in rear-end collisions. In the test protocol, a simplified triangular acceleration is applied to the sled. This study clarifies whether biofidelic rear-impact dummy II (BioRID II) measurements obtained for simplified triangular acceleration reflect car-to-car rear-end impacts in real-world accidents in Japan. We conducted a car-to-car rear-end impact experiment and a simplified-triangular-acceleration sled test. Our results indicate that the time series of dummy responses were approximately consistent in the two test conditions. The neck injury criterion (NIC) and maximum acceleration of the head and T1 measured using the BioRID II dummy were similar in the car-to-car and sled experiments. This revealed that the J-NCAP test protocol using simplified triangular acceleration reflects the car-to-car rear-end impact experiment using Japanese cars, in terms of the NIC and maximum acceleration of the head and T1.

A hybrid electric vehicle (HEV) is a vehicle that combines a conventional propulsion system with an on-board rechargeable energy storage system to achieve better fuel economy than a conventional vehicle HEVs do not have limited ranges like battery electric vehicles, which use batteries charged by an external source. The different propulsion power systems may have common subsystems or components. The objective of this study is to compare the fuel economies of a conventional step van, a series hybrid electric step van (HESV), and a parallel HESV by calculating the fuel consumption using the ADVISOR software by NREL. We also showed the results of the vehicles in different driving cycles including the Central Business District bus cycles, the New York City Cycle, and the US EPA City and Highway cycles.

As emissions regulations are tightened, various engine and emission reduction improvements have been applied. The reduction of particulate matter (PM), a major diesel engine emission, relies solely on after-treatment in the diesel particulate filter (DPF). It is not possible to satisfy current exhaust regulations without a DPF installed downstream of a diesel engine. Therefore, in the design of DPF systems, thermal stability and durability at the high temperatures experienced during the regeneration process are considered critical in determining the substrate material, as any defects (cracking, damage, or melting) cause increased pollutant emissions. In this study, the regeneration characteristics of 10.5 in cordierite DPF substrates applied in large commercial vehicles were investigated according to pore structure. The pore structure was changed while maintaining the thermal expansion coefficient and thermal properties by changing the particle size of talc during fabrication. Two different substrate compositions were evaluated and applied in a 6-L diesel engine to analyze their thermal characteristics during normal and uncontrolled (drop-to-idle) regeneration according to PM loading. The improvement in pore structure was observed to increase the PM oxidation rate under normal regeneration and extended the PM loading limit under uncontrolled regeneration.

This study developed a method to evaluate the sound quality of the warning sound masked by background noise considering the masking effect. The warning sound of an electric vehicle is required by law for the safety of pedestrians. Therefore, the warning sound becomes an additional noise pollution source if it is designed as an annoyance. On the other hand, if the sound is designed with a low sound pressure level, pedestrians will not recognize the approach of vehicle due to background noise. To avoid nose pollution and permit the detectability of an approaching vehicle, a method for evaluating the annoyance and detectability of an electric vehicle is required. In this paper, the whine index evaluating the whine sound masked by the background was developed and used as a sound metric. This metric was employed for the development of an annoyance index and detectability index for electric vehicles.

In the last decade, vehicle identification systems have become a central element in many applications involving traffic law enforcement and security enhancement, such as locating stolen cars, automatic toll management, and access control to secure areas. As a method of vehicle identification, license plate recognition (LPR) systems play an important role and a number of such techniques have been proposed. In this paper, we describe a method for segmenting the main numeric characters on a license plate by introducing dynamic programming (DP) that optimizes the functionality describing the distribution of the intervals between characters, the alignment of the characters, and the threshold difference used to extract the character blobs. The proposed method functions very rapidly by applying the bottom-up approach of the DP algorithm and also robustly by minimizing the use of environment-dependent image features such as color and edges.

Neck fracture is a major cause of death in traffic accidents. This pattern of injury normally occurs in a frontal collision or overturn of a vehicle. This study investigates the case of a neck fracture from a low-speed collision. In the examined case, the passenger in the front seat of the car fractured his neck and died. He did not have his seatbelt on when the vehicle slipped on a frozen road surface on a downward slope of a hill and impacted into the shoulder of the road at low speed. In this type of collision, an occupant’s body will be impacted by the windshield or other interior trim of the car. However, in this case, rather unusually, neither body tissue nor fiber remained although the collision involved a broken windshield. Thus, the reason for the passenger death was unidentified. This study applied the computer simulation package Madymo for analyzing the accident. The result of the simulation was that the passenger, who did not wear a seatbelt, moved forward due to inertia. The upper part of the passenger then rotated and lifted when the knee contacted with the dashboard. By evaluating the structural deformation of the vehicle at the front, we deduced that the collision velocity was 30 km/h. Through a computational experiment that was undertaken using Madymo 7.0, NIC was estimated to be 240 m2/s2. This result far exceeded the threshold for neck injuries. In particular, in comparison with whiplash injuries, when the passenger’s head directly impacts the roof following a rear-end collision, the bending moment through hyperextension of the neck is greatly increased. In this study, we concluded that the manner of death was the hyperextension of the neck, as the passenger’s head contacted the roof from underneath.

This paper deals with a novel clutch mechanism for transmission applications, which aims at easy application of the transmission as the micro-electric vehicle models expand in variety. The new mechanism actuated by the torque and rotational inertia of the traction motor instead of the conventional hydraulic or electronic actuator and features a simple structure compared to the conventional mechanism. The operating principle, structure and mathematical modeling of the new clutch mechanism are presented, and verification of mathematical modeling was done through comparison of experimrntal and analytical results. To investigate the automotive suitability of the new clutch mechanism, the shift characteristics are analyzed by longitudinal directional vehicle dynamic model applying new clutch mechanism. As a result of the analysis, it was confirmed that the shift shock absorbing ability and required time for shifting are applicable to the vehicle transmission.

A total of 96 tests were conducted using a driving simulator with six male volunteers. The driving simulator produced a series of 4.8-second cycle motions that combines roll (Rx) and sway (Dy). The cycle motions were produced in four levels of intensity by linearly adjusting the amplitude of roll and sway (from 0.15 to 0.40 g). Meanwhile, the subjects remained either reactive or proactive. An IMU sensor was attached to the forehead of the subjects and measured head kinematics at 256 Hz. The roll, yaw, and sway motions of the head were obtained in 10 cycles of the steady-state section. All motions showed longer delay with respect to the simulator under the stronger floor intensity. In the reactive strategy, normalize values tended to be smaller as the intensity of the floor increased. While, in the proactive strategy, the values stayed constant regardless of the intensity. The CORrelation and Analysis (CORA) score showed a lower inter-subject variation and higher repeatability in higher intensity. Depending on the two strategies and movement of the head, comparison of inter-subject variation and repeatability showed statistically significant differences.