For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.

No abstract

Background: At present, research comparing robot-assisted thoracic surgery (RATS) and video-assisted thoracoscopic surgery (VATS) in lobectomy/segmentectomy for lung cancer is insufficient. This paper aimed to compare the safety, short-term efficacy, quality of life (QoL), and delayed complications at 6 weeks postoperatively via a retrospectively controlled study by a single surgeon.Methods: A total of 110 non-small cell lung cancer (NSCLC) cases from December 2020 to May 2021 were enrolled in this retrospective study, and were divided into RATS and VATS groups (both three-port procedures) according to the patients' preference. The propensity-score matching method was applied to control the potential differences. The patients were treated with lobectomy/segmentectomy for lung cancer by RATS or VATS, and the safety outcomes were evaluated. The follow-up was initiated after surgery, and the outcome assessments including hospitalization costs, short-term efficacy, pain and QoL, were collected and analyzed.Results: Both matched groups achieved a R0 resection rate of 100%. The average operation time of the RATS group was 21 minutes shorter than VATS (P<0.01), and the average hospitalization costs of the RATS group was 17,746 China Yuan higher than VATS (P<0.01). Furthermore, the visual analogue pain scores of the RATS group were lower than those of the VATS group at 1 day and 6 weeks postoperatively (2.53±0.86 vs. 3.88±0.88 and 0.35±0.65 vs. 0.74±0.88, respectively, P<0.05). Moreover, the core QoL scale score for cancer patients in the RATS group were higher than those of the VATS group at 6 weeks postoperatively (98.64±5.73 vs. 93.02±15.21, respectively, P<0.05). No significant differences were observed in the other indicators.Conclusions: Despite its high cost, RATS showed considerable potential for reducing the operation time and improving the QoL of patients. Meanwhile, RATS and VATS exhibited similar perioperative safety and short-term efficacy in lobectomy and segmentectomy.