The uncertain parameters of automotive powertrain mounting systems (PMSs) may involve imprecise information (e.g., incomplete, different and conflicting information) in engineering practice. An effective approach is proposed for the reliability-based robust design optimization (RBRDO) of uncertain PMSs involving imprecise information. In the proposed approach, the imprecise information of uncertain parameters is firstly addressed and combined based on evidence theory, and the uncertain parameters are treated as evidence variables. Then, an uncertainty analysis method named evidence perturbation-central difference method (EPCDM) is derived to fast estimate the mean intervals, standard deviation intervals, and the belief and plausibility measures related to system inherent characteristics. A reference method named evidence-Monte Carlo method (EMCM) is developed to verify the effectiveness of EPCDM. Next, to conduct robustness design, the weighted sum of the lower bounds of means and the upper bounds of standard deviations of system inherent characteristics are taken to construct optimization objective; while to perform reliability design, the belief measures related to system inherent characteristics are used to create reliability constraints. Afterwards, a nested RBRDO model is established to explore the optimum design of the PMS, which considers both reliability and robustness simultaneously. The nested PBRDO can be effectively simplified based on EPCDM. The effectiveness of the proposed approach is finally demonstrated by the application example.
The effect of a rare earth (RE) surface treatment on the mechanical and tribological properties of carbon fiber (CF) reinforced polytetrafluoroethylene (PTFE) composites was experimentally investigated. The tensile properties of the CF reinforced PTFE (CF/PTFE) composites treated with air oxidation and RE modifier were superior to those of untreated CF/PTFE composites, while RE treatment was most effective in promoting the tensile strength and strain at break of the CF/PTFE composite. The bending strength of the RE treated CF/PTFE composite was improved by about 16% compared with that of untreated composites, while 2% improvement was achieved by air oxidation. Under oil-lubricated conditions, RE treatment was more effective than air oxidation to reduce the friction coefficient and wear of PTFE composite. RE treatment effectively improved the interfacial adhesion between CF and PTFE. The strong interfacial coupling of the composite made CF not easy to detach from the PTFE matrix, and prevented the rubbing-off of PTFE, accordingly improved the friction and wear properties of the composite. 相似文献
Based on the three rotational degrees (video in three dimensions, on the X, Y and Z axes) of freedom provided by VR, the viewer is free to control the viewing point and has six degrees of freedom (6DoF). When watching a sports game, the audience is no longer limited by the position of the camera, and can freely choose the viewing angle and position just like watching in the real world, which can greatly improve the immersion of viewing. However, the major barrier that prevents 6DoF video live from being industrialized lies in the extremely high computational complexity, of which multi-view depth estimation and Depth Image Based Rendering (DIBR) is difficult to realize. And existing devices do not have hardware interfaces that support multi-views coding technology. Therefore, we need new technologies for depth estimation and virtual view synthesis, and we need to use existing hardware coding/decoding interfaces to reduce power consumption. In this paper, we provide a 6DoF live video system, which includes multi-view depth estimation technique based on unsupervised learning, virtual viewpoint real-time rendering technology and 6DoF video coding. Experimental results demonstrate that our proposed acceleration method can speed up the original depth estimation algorithm by more than 34x, and can speed up the original DIBR algorithm by more than 168x. With our 6DoF video coding method, experimental results show that the bit rate achieves an average of 70%, 64%, 33%, 60% and 66% bitrate saving for AVC, HEVC, AV1, AVS3, VVC codec standard respectively.
