For the manufacturing of high strength automobile body safety parts, a digitally controlled pilot production system for the hot stamping process was developed, including an electro-servo press, a numerically controlled heating furnace, a blank conveying system and a synchronized production line control system. By using the in-house developed hot stamping production system, automobile B pillars were manufactured from a proprietary high strength steel developed by Wuhan Iron and Steel (Group) Corporation. The steel blank was austenized in the furnace at 950°C for 5 min, followed by hot stamping. The overall cooling rate of the heated blank was above 35°C s -1 during the hot stamping process, which ensured a uniform martensitic microstructure with an average hardness above 460 HV1, a room temperature of tensile strength of 1489MPa and an elongation of 6.87%. The deviation of the formed part from the 3-D model is in the range between +0.623mm ~ -0.826mm.
Review question / Objective: To examine whether cancer patients with COVID-19 may be at an increased risk of severe illness and whether cancer is associated with mortality in patients with COVID-19.Condition being studied: Cancer patients are considered a highly vulnerable population in the COVID-19 epidemic, but the relationship between cancer and the severity and mortality of patients with COVID-19 remains unclear.This study aimed to explore whether cancer patients INPLASY 1 International Platform of Registered Systematic Review and Meta-analysis Protocols INPLASY PROTOCOL Impact of cancer on mortality and severity of COVID-19: a protocol for systematic review and meta-analysis
En-route travel choice behavior is one of the primary travel behavior over residential daily trips. Providing traffic information will exert an impact on en-route travel choice behavior. Through comparative studies, the paper reveals that RP/SP joint survey and the disaggregate model are two suitable methods. On the basis of that, the paper develops a scheme for RP/SP joint survey and a Multinomial Logit (MNL) Model for modeling and analysis. The aim of the paper is to provide theoretical and practical support for the research of en-route travel choice behavior with traffic information in China.
Full-scaled hot stamping dies were designed for a vehicle bumper, based on evaluation of cooling system by FE simulation and the temperature variation assessment by analytical model. The blank shape was gained using inverse algorithm and well-designed according to production practice. Experiments were conducted to verify the reliability of both the die and blank design, as well as tests for microstructure and mechanical properties of the hot-stamped part. Results show that, CAE analysis provides a robust support for hot stamping die and blank design; Position stability of hot blank is greatly improved during robotic transport process after shape designing; Metallographic analysis demonstrates the hot-stamped bumper obtained a fully martensitic microstructure, its tensile strength is about 1550 MPa, microhardness is 47.5 HRC, and the elongation is up to 6%.
To explore the clinical value of contrast-enhanced ultrasound (CEUS) in the differential diagnosis of benign and malignant subpleural pulmonary lesions (SPLs).Among 959 patients with SPLs who were scheduled to undergo ultrasound-guided puncture in our department between January 2019 and June 2019, 506 patients were included and their B-mode ultrasound and CEUS features, including the lesion's location, size, margin, echo, perfusion pattern of ultrasound contrast agent, degree of enhancement, homogeneity, vascular signs, and necrosis, were retrospectively investigated. All malignant cases were diagnosed by pathology, while benign cases were diagnosed by two respiratory physicians after comprehensive analysis of pathology, etiology, imaging, and clinical symptoms. Statistical differences in these features between the benign and malignant groups were then analyzed.There were 506 cases in this study, including 219 benign cases and 287 malignant cases. Among them, 351 were males and 155 were females, with an average age of 59 ± 16 years. There were statistically significant differences between benign and malignant groups in the perfusion pattern, the degree of enhancement, and vascular signs. The features of the malignant group included local-to-whole perfusion pattern, hypo-enhancement, and curly hair sign, while those of the benign group included a centrifugal perfusion pattern, iso-enhancement and hyper-enhancement, and dendritic sign. There was no statistically significant difference between the two groups in homogeneity and necrosis.CEUS enhancement mode is different between benign and malignant SPLs, which can provide supplementary information for the differential diagnosis of SPLs in the existing imaging diagnosis.
The hot forming parts of high strength steel are difficult to cut with the presses and the traditional high-energy beam due to its high tensile strength which can be up to 1500Mpa and its complex structure. And the 3D laser cutting is an effective way to solve the problem. However some problems in the laser process affect the efficiency and quality seriously, including interference between the robot arms and the cutting head with the untrimmed parts, difficulty in determining the entry point and over burning etc. In this research three measures are taken to cut the anti-collision beam, including using photogrammetric technology to get its uncutted 3D model for offline programming to avoid interference, selecting appropriate entry point to trim without interrupt, amending normals and adjusting the process parameters at corners to prevent over burning. The results show that the efficiency and quality are improved and a creative new offline programming method is put forward.
Computational Fluid Dynamics (CFD) method was adopted to establish the three dimensional model for cathode gas channel of planar SOFC and simulate the gas flow in the channel of a single cell. A quantitative analysis method was presented to research the status of gas flow. The characteristics and diagram of velocity change were obtained by using the quantitative analysis method. Furthermore, it was found that gas leak has a negative effect on the uniformity of gas flow, which is more obvious in the region near the leak side.
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