Emergency braking on a low coefficient of friction or split-mu road surface, the semi-trailer may push the tractor from behind until it spins round and faces backwards, and a jackknife accident occurs. In this paper, the tractor semi-trailer kinematics was analyzed and a 3-dof of tractor semi-trailer model was used to design a state observer to estimate the articulation angle. To avoid a jackknife, the four-channel ABS which can produce maximum braking force will be switch to three-channel ABS according the estimated articulation angle. The virtual prototyping simulation results show that the jackknife control system can improve the tractor semi-trailer lateral stability under emergency braking and shorten the stop distance dramatically on split-mu road surface at high speed.
Besides the performances of handling, stability, ride comfort, power and fuel economy, the sound pressure levels in the automobile passenger compartments heavily influence the customer’s purchasing decision. The interior acoustics of automobile passenger compartment was analyzed in this paper. The frequency response analysis was performed on the vehicle body due to road roughness. The frequency response of vehicle body’s output spectrum, nodes’ velocity is used as the boundary condition of the acoustic cavity. With boundary element method and acoustic transfer vector method, the panel acoustic contribution was analyzed. By modifying the stiffness, damping or mass of the corresponding panel, the acoustic pressure levels at the driver’s and passenger’s ear were decreased.
Fusarium ear rot in maize (Zea mays L.) is a serious disease in all maize-growing areas worldwide. A total of 454 fungal strains were isolated from 69 commercial maize hybrids grown in Harbin, China, and comprised Fusarium subglutinans (34.8%), F. proliferatum (31.3%), F. verticillioides (20%), F. graminearum (9.7%), and F. equiseti (4.2%). Among them, a complex of multiple species, F. subglutinans, F. proliferatum, and F. verticillioides are the dominant fungi causing ear rot. Among 59 commercial maize hybrids, eleven hybrids (18.6%) were found to be highly resistant to Fusarium ear rot. Simple sequence repeat (SSR) analysis using six pairs of primers resulted in 24 reproducible bands and cluster analysis separated the maize hybrids into eight groups. There was little genetic variation associated with disease resistance. No correlation was found between genetic diversity and disease resistance.
The human spinal column is a highly complex and sophisticated system both from an engineering and neurological point of view, and provides a source of biomimetic inspiration for analysis of its function in trauma scenarios. A three-dimensional multi-body model of the 50th percentile male human and discretized neck were built for the study on cervical spine injuries in vehicle frontal impact. The discretized neck includes of cervical spine vertebrae, intervertebral discs, ligaments, and muscles. Following motor front crash evaluations, a finite element vehicle model was propelled straight ahead into a concrete barrier at a speed of 50 km/h. The longitudinal velocity of driver seat was decreased due to the absorbing energy function of the crumple zones. A Hybrid III adult male dummy was seated on a sled, restrained using safety belt, and longitudinal velocity measured from frontal impact was applied to simulate cervical spine injuries. The disk bending loads, interspinous ligament loads and disk shear strain of the cervical spine were analyzed in this paper.
The paper presents a vehicle dynamics control strategy devoted to prevent vehicles from spinning and drifting out. With vehicle dynamics control system, counter braking are applied at individual wheels as needed to generate an additional yaw moment until steering control and vehicle stability were regained. The Linear Quadratic Regulator (LQR) theory was designed to produce demanded yaw moment according to the error between the measured yaw rate and desired yaw rate. The results indicate the proposed system can significantly improve vehicle stability for active safety.
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