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ABSTRACTIn the automotive industry, the extended design and iteration cycles for integrated chassis typically span 2–3 years, creating a misalignment with swiftly changing market demands. Wire arc additive manufacturing (WAAM) technology presents a viable alternative, overcoming the limitations of conventional chassis production. Our holistic framework significantly condenses the design, optimisation, and validation stages for automotive chassis. Initially, a ground structure method is utilised to outline and generate a skeleton chassis. We then utilise the OpenCV image processing method to select a hollow skeleton chassis with minimal material occupancy (0.476) and suspension printing. Subsequently, we assess the influence of printing radian variations by the robotic arm on the microstructure and stress, employing a cellular automaton-finite element (CA-FE) model at the 150th and 200th layer benchmarks. A Kalman filter (KF) is also implemented to fine-tune the printing radian in regions with coarse grain structures and elevated solute concentrations. The process concludes with collision and modal simulation verifications of the skeleton chassis, affirming the optimisation's success. This streamlined methodology allows the completion of the chassis design and manufacturing cycle within a remarkably condensed time frame of one week, accelerating the development process by a factor of 120.

AbstractThe Wenchuan earthquake triggered many landslides, which caused many casualties and led to considerable property losses. Due to the compositionality of the hypocenter mechanism of the Wenchuan earthquake, research on the effects of a composite hypocenter on the dynamic responses of landslides is urgently necessary. Using geological field investigations, a block discrete element method simulation, and related theoretical analysis, the dynamic formation mechanism and main controlling mechanical factors of the Tangjiashan landslide were revealed. The results demonstrated the following. Firstly, the dynamic responses of the slope involved progressive deformation, critical failure, disintegration, fragmentation, collision, climb, return, and accumulation. Secondly, when the earthquake lasted for approximately 23 s, the critical failure occurred, and the sliding mass near the shoulder reached a vertical acceleration of approximately 2.8 g at this time. Thirdly, the second and third subhypocenters contributed to the progressive deformation and critical failure, and vertical seismic forces were dominant contributions to these responses. Fourthly, the disintegration, fragmentation, collision, climb, return, and accumulation were mainly controlled by the self-gravity and local topography and were slightly influenced by subhypocenters. Based on these conclusions, the study of the dynamic formation mechanism of this type of landslide has increased the level of understanding.

Catastrophic landslides have occurred frequently in the karst areas of Southwestern China for these years, which makes it urgently necessary to reveal their triggering mechanisms. The universal distinct element code (UDEC) was used to simulate whole response of the Pusa landslide during its underlying coal-seam mining. The results are as follows. First, under the given pre-conditions, when coal seams beneath the original slope were mined from bottom to top, caving zone, fracture zone, and deformation zone overlying the goaf gradually expanded; and as the uppermost layer was mined, the deformation, which was apparently characterized by subsidence and clockwise rotation, overwhelmed the slope. Second, under action of the heavy rainfall, the deformed slope, which was affected by the goaf, behaved further progressive deformation characterized by subsidence and clockwise rotation as a whole. Third, with continuous action of near stoping blasting vibrations, the more-deformed slope, which had been influenced by the goaf and the heavy rainfall, behaved continuous progressive deformation, critical failure, shattering, ejection, debris flow, and accumulation. The deformation exhibited significant subsidence, clockwise rotation, and collapse. These responses were verified by the field reconnaissance. It is the first time to explore dynamic triggering mechanism of the landslide triggered by the vibrations.

ABSTRACTThe mutations in the SARS-CoV-2 virus genome during COVID-19 dissemination are unclear. In 788 COVID-19 patients from Zhejiang province, we observed decreased rate of severe/critical cases compared with patients in Wuhan. For mechanisms exploration, we isolated one strain of SARS-CoV-2 (ZJ01) from a mild COVID-19 patient. Thirty-five specific gene mutations were identified. Phylogenetic and relative synonymous codon usage analysis suggested that ZJ01 may be a potential evolutionary branch of SARS-CoV-2. We classified 54 global virus strains based on the base (C or T) at positions 8824 and 28247 while ZJ01 has T at both sites. The prediction of the Furin cleavage site (FCS) and sequence alignment indicated that the FCS may be an important site of coronavirus evolution. ZJ01 mutations identified near the FCS (F1-2) caused changes in the structure and electrostatic distribution of the S surface protein, further affecting the binding capacity of Furin. Single-cell sequencing and ACE2-Furin co-expression results confirmed that the Furin expression was especially higher in glands, liver, kidneys, and colon. The evolutionary pattern of SARS-CoV-2 towards FCS formation may result in its clinical symptom becoming closer to HKU-1 and OC43 caused mild flu-like symptoms, further showing its potential in differentiating into mild COVID-19 subtypes.