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Mechanism analysis and improved model for stick-slip friction behavior considering stress distribution variation of interface
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作者 Jingyu Han jiahao ding +1 位作者 Hongyu Wu Shaoze Yan 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第3期350-363,共14页
Studying the evolution of interface contact state, revealing the “black box” behavior in interface friction and establishing a more accurate friction model are of great significance to improve the prediction accurac... Studying the evolution of interface contact state, revealing the “black box” behavior in interface friction and establishing a more accurate friction model are of great significance to improve the prediction accuracy of mechanical system performance. Based on the principle of total reflection, a visual analysis technology of interface contact behavior is proposed. Considering the dynamic variation of stress distribution in interface contact, we analyze the nonlinear characteristics of contact parameters in different stages of stick-slip process using the above-mentioned experimental technology. Then,we find that the tangential stiffness of the interface is not a fixed value during the stick-slip process and the stress distribution variation is one of the important factors affecting the tangential stiffness of interface. Based on the previous experimental results, we present an improved stick-slip friction model, considering the change of tangential stiffness and friction coefficient caused by the stress distribution variation. This improved model can characterize the variation characteristics of contact parameters in different stages of stick-slip process, whose simulation results are in good agreement with the experimental data. This research may be valuable for improving the prediction accuracy of mechanical system performance. 展开更多
关键词 stress distribution tangential stiffness friction coefficient STICK-SLIP friction model
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孟德尔随机化研究精神分裂症与自杀或故意自残的因果关系 被引量:8
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作者 丁佳豪 章梦琦 +5 位作者 郝明霞 龙丽婷 陈晓 田荣燊 张爽 苑杰 《中华精神科杂志》 CAS CSCD 北大核心 2023年第1期32-39,共8页
目的采用孟德尔随机化(Mendelian randomization, MR)方法研究精神分裂症与自杀或故意自残的双向因果关系。方法利用大规模全基因组关联研究(genome-wide association studies, GWAS)汇总数据, 选择相互独立且与欧洲血统人群精神分裂症... 目的采用孟德尔随机化(Mendelian randomization, MR)方法研究精神分裂症与自杀或故意自残的双向因果关系。方法利用大规模全基因组关联研究(genome-wide association studies, GWAS)汇总数据, 选择相互独立且与欧洲血统人群精神分裂症及自杀或故意自残相关的遗传位点作为工具变量。精神分裂症GWAS数据包括76 755例精神分裂症患者和243 649名对照者。自杀或故意自残的GWAS数据包括1 058例自杀或故意自残患者和307 942名对照者。应用逆方差加权法(inverse variance weighted, IVW)及加权中位数法进行MR分析, 以比值比作为评价指标对精神分裂症及自杀或故意自残的双向因果关系进行探讨。CochranQ检验评估各个单核苷酸多态性(single nucleotide polymorphism, SNP)之间的异质性。使用孟德尔随机多态性残差和离群值(Mendelian randomization, pleiotropy residual sum and outlier, MR-PRESSO)检测SNP异常值。MR-Egger截距测试检验SNP的水平多效性。"留一法"敏感性分析检验MR研究是否受单个SNP的影响。结果 IVW显示, 精神分裂症可增加自杀或故意自残的风险(OR=1.297, 95%CI=1.154~1.457, P<0.001), 且在加权中位数法中被证实(OR=1.232, 95%CI=1.038~1.461, P=0.017)。反之, 自杀或故意自残与精神分裂症无关(OR=0.969, 95%CI=0.927~1.012, P=0.157), 同样被加权中位数法证实。CochranQ检验、MR-PRESSO检测和MR-Egger截距测试显示工具变量之间不存在异质性或水平多效性;"留一法"敏感性分析证实, 没有单个SNP对整体的结果有较大的影响。结论精神分裂症与自杀或故意自残的风险增加有显著的因果关系。 展开更多
关键词 精神分裂症 自杀 自残 孟德尔随机化 因果推断
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