Ride comfort and segmental vibration transmissibility analysis of an automobile passenger model under whole body vibration.

The examination of seated occupants' ride comfort under whole-body vibration is a complex topic that involves multiple factors. Whole-body vibration refers to the mechanical vibration that is transmitted to the entire body through a supporting surface, such as a vehicle seat, when traveling on rough or uneven surfaces. There are several methods to assess ride comfort under whole-body vibration, such as subjective assessments, objective measurements, and mathematical models. Subjective assessments involve asking participants to rate their perceived level of discomfort or satisfaction during the vibration exposure, typically using a numerical scale or questionnaire. Objective measurements include accelerometers or vibration meters that record the actual physical vibrations transmitted to the body during the exposure. Mathematical models use various physiological and biomechanical parameters to predict the level of discomfort based on the vibration data. The examination of seated occupants ride comfort under whole-body vibration has been of great interest for many years. In this paper, a multi-body biomechanical model of a seated occupant with a backrest is proposed to perform ride comfort analysis. The novelty of the present model is that it represents complete passenger by including thighs, legs, and foot which were neglected in the past research. A multi-objective firefly algorithm is developed to evaluate the biomechanical parameters (mass, stiffness and damping) of the proposed model. Based on the optimized parameters, segmental transmissibilities are calculated and compared with experimental readings. The proposed model is then combined with a 7-dofs commercial car model to perform a ride comfort study. The ISO 2631-1:1997 ride comfort standards are used to compare the simulated segmental accelerations. Additionally, the influence of biomechanical parameters on most critical organs is analyzed to improve ride comfort. The outcomes of the analysis reveal that seated occupants perceive maximum vibration in the 3-6 Hz frequency range. To improve seated occupants' ride comfort, automotive designers must concentrate on the pelvis region. The adopted methodology and outcomes are helpful to evaluate protective measures in automobile industries. Furthermore, these procedures may be used to reduce the musculoskeletal disorders in seated occupants.

Association of gene polymorphism in detoxification enzymes and urinary 8-OHdG levels in traffic policemen exposed to vehicular exhaust.

CONTEXT: With rapid economic growth and massive development of transportation, the number of automobiles has greatly increased. Traffic police are the one of the vulnerable groups predominantly exposed to vehicular exhaust during traffic control. OBJECTIVE: The present study is aimed to study the relation between occupational exposure to vehicular exhaust and oxidative stress (OS) in traffic police. We investigated the levels of 8- hydroxydeoxyguanosine (8-OHdG), one of the most sensitive biomarkers for measuring OS and the association between polymorphisms in Cytochrome P450 (CYP) and Glutathione S-Transferase (GST) genes that are known to play a significant role in the activation and detoxification of xenobiotics. MATERIALS AND METHODS: 148 non smoking male traffic policemen and 135 control subjects were selected for this study. The 8-OHdG levels were analyzed by liquid chromatography with electrochemical detection method. Gene polymorphism was detected by multiplex PCR and RFLP method. RESULTS: 8-OHdG levels were found to be increased in traffic police with increase in the years of service in traffic control (p = 0.02) when compare to the controls. The results showed a significant increase in urinary 8-OHdG levels in mutated CYP1A1m1 (p < 0.007) and null GSTM1 (p < 0.01) genotypes. However the genotype frequencies of CYP1A1 m2 and GSTT1 genes did not vary in both exposed and control groups. CONCLUSION: Our study suggests that exposure to vehicular exhaust over a period of time increases oxidative stress and subsequently induces oxidative DNA damage in traffic policemen. Preventive and therapeutic strategies may be considered for traffic policemen to minimize the adverse effects due to vehicular exposure.