Abstract. The purpose of this study was to investigate the vibration characteristics of both front and back vented brake discs with physically different shapes. In accordance with theory, the heat transfer rates of the two types of brake disc were different and played an important role in deformation during usage. A dynamometer was used as an engineering tool for the experimental work, with boundary conditions according to the Japanese Automobile Standard JASO C406. One degree of freedom (DOF) acceleration signals on the brake calipers were analysed. Results indicated that the back vented brake disc reduced the vibration by up to 43.5% compared to the front vented brake disc with braking temperature at 200C, initial braking speed 50 km/h and hydraulic pressure of 4 MPa. Hydraulic pressure at 4 MPa generated the maximum vibration. Initial braking speed and braking temperature were also important factors.
An accident between pedestrians and city buses is one cause of severe casualties in Thailand. To discover the causes of the city bus collisions with pedestrians, 22 accident cases which occurred in Bangkok and suburban areas from January 2012 to July 2013 were reconstructed and investigated. In this study, the impact speeds were estimated by data correction at the incident scene using the kinematic measurement device. Besides, these collision cases were categorized by the difference between low-and high-located windshield types with regards to the behavior and body region of pedestrian injuries. Moreover, it was discovered that pedestrian injuries were more severe at impact speeds of approximately at 20 to 50 km/h. However, the 90th percentile impact speed was not over 30 km/h. Moreover, there were 7 cases among 21 collisions (33%) in the early afternoon time (12.01am-3.29pm) of driving period, which was almost the end of the morning shift. That was probably the result of long durations of driving, a condition which is a significant cause of fatigue-related accidents.
Rubber tree is an outstanding product in commercial area of Thailand. Tyre is one of the prominent and downstream products as components in the automotive industry with a high production capacity. While tyres are used widely, a regulation for the rolling resistance of tyres has been set up by the European Commission. Therefore, the operators must test their products. By the high costs for the testing before certification, the researchers realize the limitation of the test equipment suffering with the small and medium enterprises that do not have access to check their tyres. This is the weakness of the tyre industry in Thailand. Therefore, the low-cost of tyre rolling resistance testing machine has been built in accordance with the UNECE Regulation No. 117 which is accepted worldwide. As a result, the in-house tyre rolling resistance testing machine is compared with the imported one in terms of production cost. The budget can be reduced up to 50% since the test equipment can be produced with currently technology in the country. Moreover, this is the self-reliance of technological machinery industry. For the working result, it was found that the vibration level of tyre rolling resistance testing machine consented to the standard ISO 10816. Besides, the experimental results of tyre rolling resistance coefficient is compliance with the requirements UNECE Regulation No. 117 Annex 6 and also verified by the international authority (TUV Rheinland Thailand Ltd). It can reduce the limitation in terms of the testing and also support the economic expansion of the production of quality tyres in the country to be accepted in international level.
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