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A kind of CAD/CAE integrated modeling method based on feature is proposed. Firstly, analysis features are attached to CAD model of part and standard part library is formed. Secondly, the CAD model is created using standard parts. Thirdly, geometry information of analysis features is extracted from CAD model and is reconstructed automatically under CAE environment. Finally, based on feature-based meshing and combination technique, CAE model is built quickly. A prototype software for large-scale antenna structure (LSAS) CAD/CAE integrated modeling has been developed and used in performance analysis of a 16-meter-diameter LSAS. The method has been proved to be useful for improving speed, accuracy and consistency of complicated structure CAE modeling notably.

A novel algorithm, which can check the collision point of rigid objects continuously and solve the problem of penetration and crossing in collision detection effectively, is presented in this paper. At each simulation moment, the adaptive test lines (ATLs) are first constructed based on the velocity vector of the moving object and then the intersection between the ATLs and the environment is calculated. The collision happens when the intersection is not empty and the collision point is obtained through crossing-frame processing. By checking the interference between body and ATLs instead of bodies, we greatly improve the detection efficiency. It avoids missing collisions for an object with arbitrary shape or in any motion states. Simulation results show that our algorithm runs faster than the general continuous collision detection algorithms and has similar detection effects to the swept volume algorithm.

BackgroundFor patients with obscure gastrointestinal bleeding (OGIB), finding the bleeding site is challenging. Balloon-assisted enteroscopy (BAE) has become the preferred diagnostic modality for OGIB. The long-term outcome of patients with negative BAE remains undefined. The present study aimed to evaluate the long-term outcomes of patients with negative BAE results for OGIB and to clarify the effect of further investigations at the time of rebleeding with a systematic review and meta-analysis of the available cohort studies.MethodsStudies were searched through the PubMed, EMBASE, and Cochrane library databases. The following indexes were analyzed: rebleeding rate after negative BAE, rebleeding rate after different follow-up periods, the proportion of patients who underwent further evaluation after rebleeding, the percentage of patients with identified rebleeding sources, and the percentage of patients with rebleeding sources in the small intestine. Heterogeneity was assessed using the I2 test.ResultsTwelve studies that involved a total of 407 patients were included in the analysis. The pooled rebleeding rate after negative BAE for OGIB was 29.1% (95% CI: 17.2–42.6%). Heterogeneity was significant among the studies (I2 = 88%; p < 0.0001). The Chi-squared test did not show a difference in rebleeding rates between the short and long follow-up period groups (p = 0.142). The pooled proportion of patients who underwent further evaluation after rebleeding was 86.1%. Among the patients who underwent further evaluation, rebleeding sources were identified in 73.6% of patients, and 68.8% of the identified rebleeding lesions were in the small intestine.ConclusionA negative result of BAE in patients with OGIB indicates a subsequently low risk of rebleeding. Further evaluation should be considered after rebleeding.

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