Multi-objective optimization of all-wheel drive electric formula vehicle for performance and energy efficiency using evolutionary algorithms

A new method based on constraint multi-objective optimization using evolutionary algorithms is proposed to optimize the powertrain design of a battery electric formula vehicle with an all-wheel independent motor drive. The electric formula vehicle has a maximum combined motor power of 80 kW, which is a constraint for delivering maximum vehicle performance with minimal energy consumption. The performance of the vehicle will be simulated and measured against different driving events, that is, acceleration event, autocross event, and endurance event. Each event demands a different aspect of performance to be delivered by the motor. The respective event lap time or energy rating will be measured for performance assessment. In this study, a non-dominated sorting genetic algorithm II and constrained multi-objective evolutionary algorithm based on decomposition by using differential evolution are employed to optimize the motor transmission ratio, motor torque scaling, and downforce scale of both front and rear wheels against the acceleration event to minimize energy consumption and event lap time while constraining the combined motor power of all wheels to not exceed 80 kW. The optimization will be performed through software-in-the-loop between MATLAB and VI-Grade, where the high-fidelity vehicle will be modeled in VI-Grade and optimization algorithms will be implemented on the host in MATLAB. Results show that the non-dominated sorting genetic algorithm II outperforms the constrained multi-objective evolutionary algorithm based on decomposition by using differential evolution in obtaining a wider distributed Pareto solution and converges at a relatively shorter time frame. The optimized results show a promising increase in the performance of the electric formula vehicle in completing those events with the highest combined performance scoring, that is, the lap time of acceleration events improves by 9.18%, that of autocross event improves by 6.1%, and that of endurance event improves by 4.97%, with minimum decrease in energy rating of 32.54%. © IMechE 2019

Degating of AlSi10Cu2Fe High-Pressure Die Casting Component Using Resonance Vibration Technique

The high-pressure die casting process is meant for high volume production rate mainly used in the automotive industry. An efficient method to separate the die-cast components from the main sprue and runner system is crucial to improving the productivity of the manufacturing processes. Conventionally casting components are often separated with the use of a grinding wheel machine, trimming machine or pneumatic hammer. Often these techniques require customized machine design in trimming the cast part as each die casting gate design might be different from one another, especially when there is a change in production cast model. This may incur higher set-up cost and additional configuration time. It is unfavourable in the manufacturing production line that handles small batch high variation of casting model in the small/medium casting industry. Thus, this paper introduced an alternative degating technique with the use of a shaker machine to match the resonance of the casting component natural frequency to separate the die-cast component from the casting tree. The proposed method can overcome the drawback of the conventional method by eliminating the additional configuration time required when there is a change in different casting part design. Die casting parts employed in this study were constructed by AlSi10Cu2Fe aluminium alloy. Experimental modal analysis was performed to verify the natural frequency calculated through finite element analysis. The correlated finite element model was then employed for harmonic response analysis to compute the frequency response of input excitation location against output stress response at the gate. The results from the analysis showed that the first natural frequency mode could induce a bending mode at the gate and created the highest stress concentration at the location. Next, an experiment was carried out by exciting the first natural frequency to the casting part using a shaker machine. In the experiment, the die-cast components were able to break away within 0.31 s at its first natural frequency. This observation was found to be in agreement with the simulation results, whereby the degating time of 0.27 s was obtained. Therefore, the present study has shown that an efficient degating of casting components process can be achieved via introducing a correct mode of vibration excitation. © 2019, American Foundry Society

Small Extracellular Vesicle‐Derived vWF Induces a Positive Feedback Loop between Tumor and Endothelial Cells to Promote Angiogenesis and Metastasis in Hepatocellular Carcinoma

Abstract Hepatocellular carcinoma (HCC) is a hypervascular malignancy by which its growth and dissemination are largely driven by the modulation of tumor‐derived small extracellular vesicles (sEVs). Proteomic profiling of circulating sEVs of control individuals and HCC patients identifies von Willibrand factor (vWF) to be upregulated progressively along HCC stages. Elevated sEV–vWF levels are found in a larger cohort of HCC–sEV samples and metastatic HCC cell lines compared to their respective normal counterparts. Circulating sEVs of late‐stage HCC patients markedly augment angiogenesis, tumor–endothelial adhesion, pulmonary vascular leakiness, and metastasis, which are significantly compromised by anti‐vWF antibody. The role of vWF is further corroborated by the enhanced promoting effect of sEVs collected from vWF‐overexpressing cells. sEV–vWF modulates endothelial cells through an elevated level of vascular endothelial growth factor A (VEGF‐A) and fibroblast growth factor 2 (FGF2). Mechanistically, secreted FGF2 elicits a positive feedback response in HCC via the FGFR4/ERK1 signaling pathway. The co‐administration of anti‐vWF antibody or FGFR inhibitor significantly improves the treatment outcome of sorafenib in a patient‐derived xenograft mouse model. This study reveals mutual stimulation between HCC and endothelial cells by tumor‐derived sEVs and endothelial angiogenic factors, facilitating angiogenesis and metastasis. It also provides insights into a new therapeutic strategy involving blocking tumor–endothelial intercellular communication