Recently,a description on a practicability of the Wöhler Curve Method for low-cycle fatigue of metals was given by the author.By the description and the low cycle fatigue test data of 16 MnR steel,it is important...Recently,a description on a practicability of the Wöhler Curve Method for low-cycle fatigue of metals was given by the author.By the description and the low cycle fatigue test data of 16 MnR steel,it is important to show that,for low cycle fatigue of metals,such a way that a stress-based intensity parameter calculated by the linear-elastic analysis is taken to be a stress intensity parameter,S,to establish a relationship between the stress intensity parameter,S,and the fatigue life,N,is practicable.In this paper,many metallic materials from the literature are given to show that the Wöhler Curve Method is well suitable for low-cycle fatigue analysis of metals.展开更多
The present paper deals with the problem of assessing the local influence in a growth curve model with Rao's simple covariance structure. Based on the likelihood displacement,the curvature measure is employed to e...The present paper deals with the problem of assessing the local influence in a growth curve model with Rao's simple covariance structure. Based on the likelihood displacement,the curvature measure is employed to evaluate the effects of some minor perturbations on the statistical inference, thus leading to the large curvature direction, which is the most critical diagnostic statistic in the context of the local influence analysis. As an application, the common covariance-weighted perturbation scheme is thoroughly considered.展开更多
目的:探讨成人脊柱畸形(adult spinal deformity,ASD)矫形术后早期躯体重心线(W-line)与近端交界区失败(proximal junctional failure,PJF)的相关性。方法:回顾性分析2014年6月~2019年3月在我院行手术治疗的99例ASD患者的临床资料,其中...目的:探讨成人脊柱畸形(adult spinal deformity,ASD)矫形术后早期躯体重心线(W-line)与近端交界区失败(proximal junctional failure,PJF)的相关性。方法:回顾性分析2014年6月~2019年3月在我院行手术治疗的99例ASD患者的临床资料,其中男19例,女80例。均行单纯后路长节段(固定椎体≥4个)固定融合手术,术后随访至少满2年。测量并记录所有患者术前、术后3个月及末次随访时的脊柱-骨盆参数。在脊柱全长侧位X线片上,将经外耳道口垂线定义为W-line,根据W-line不同位置分为A组、B组及C组。测量术后3个月时W-line到S1后上角水平距离(WSD)及W-line到股骨头中心连线中点的水平距离(WHD),将W-line位置进行数值转化(the numeric value of W-line,N-W-line):N-W-line=WHD/WSD。W-line位于参考点前方数值为正,反之为负。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析得出N-W-line临界值。三组患者参数进行方差分析,应用Kaplan-Meier曲线分析非PJF生存时间。结果:ROC曲线分析得出术后3个月N-W-line临界值为±0.78[敏感度=75%,特异度=75.9%,曲线下面积(the area under the curve,AUC)=0.736,P=0.003]。A组32例,N-W-line>0.78;B组49例,-0.78≤N-W-line≤0.78;C组18例,N-W-line<-0.78。A组患者骨盆入射角(pelvic incidence,PI)最小(P<0.05),术后3个月矢状面平衡距(P<0.001)、T1骨盆角(P<0.001)及骨盆腰椎匹配度(P<0.001)均显著小于其他两组患者。但随访中,A、B及C组分别有12例、3例及1例患者出现PJF,A组患者PJF发生率显著高于其他两组(12/32 vs 3/49 vs 1/18,P<0.001)。此外,A组患者非PJF生存时间显著低于其他两组患者(P=0.005,Log-rank检验)。B、C组患者W-line位置逐渐前移,脊柱-骨盆矢状位参数逐渐增大,但术后PJF发生率显著降低。结论:ASD患者矫形术后早期W-line位置可有效预测PJF发生。矫形手术后W-line偏后或过度偏前,术后随访中PJF发生率显著增加,矫形术后躯干呈轻度前屈为最佳。展开更多
文摘Recently,a description on a practicability of the Wöhler Curve Method for low-cycle fatigue of metals was given by the author.By the description and the low cycle fatigue test data of 16 MnR steel,it is important to show that,for low cycle fatigue of metals,such a way that a stress-based intensity parameter calculated by the linear-elastic analysis is taken to be a stress intensity parameter,S,to establish a relationship between the stress intensity parameter,S,and the fatigue life,N,is practicable.In this paper,many metallic materials from the literature are given to show that the Wöhler Curve Method is well suitable for low-cycle fatigue analysis of metals.
文摘The present paper deals with the problem of assessing the local influence in a growth curve model with Rao's simple covariance structure. Based on the likelihood displacement,the curvature measure is employed to evaluate the effects of some minor perturbations on the statistical inference, thus leading to the large curvature direction, which is the most critical diagnostic statistic in the context of the local influence analysis. As an application, the common covariance-weighted perturbation scheme is thoroughly considered.
文摘目的:探讨成人脊柱畸形(adult spinal deformity,ASD)矫形术后早期躯体重心线(W-line)与近端交界区失败(proximal junctional failure,PJF)的相关性。方法:回顾性分析2014年6月~2019年3月在我院行手术治疗的99例ASD患者的临床资料,其中男19例,女80例。均行单纯后路长节段(固定椎体≥4个)固定融合手术,术后随访至少满2年。测量并记录所有患者术前、术后3个月及末次随访时的脊柱-骨盆参数。在脊柱全长侧位X线片上,将经外耳道口垂线定义为W-line,根据W-line不同位置分为A组、B组及C组。测量术后3个月时W-line到S1后上角水平距离(WSD)及W-line到股骨头中心连线中点的水平距离(WHD),将W-line位置进行数值转化(the numeric value of W-line,N-W-line):N-W-line=WHD/WSD。W-line位于参考点前方数值为正,反之为负。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析得出N-W-line临界值。三组患者参数进行方差分析,应用Kaplan-Meier曲线分析非PJF生存时间。结果:ROC曲线分析得出术后3个月N-W-line临界值为±0.78[敏感度=75%,特异度=75.9%,曲线下面积(the area under the curve,AUC)=0.736,P=0.003]。A组32例,N-W-line>0.78;B组49例,-0.78≤N-W-line≤0.78;C组18例,N-W-line<-0.78。A组患者骨盆入射角(pelvic incidence,PI)最小(P<0.05),术后3个月矢状面平衡距(P<0.001)、T1骨盆角(P<0.001)及骨盆腰椎匹配度(P<0.001)均显著小于其他两组患者。但随访中,A、B及C组分别有12例、3例及1例患者出现PJF,A组患者PJF发生率显著高于其他两组(12/32 vs 3/49 vs 1/18,P<0.001)。此外,A组患者非PJF生存时间显著低于其他两组患者(P=0.005,Log-rank检验)。B、C组患者W-line位置逐渐前移,脊柱-骨盆矢状位参数逐渐增大,但术后PJF发生率显著降低。结论:ASD患者矫形术后早期W-line位置可有效预测PJF发生。矫形手术后W-line偏后或过度偏前,术后随访中PJF发生率显著增加,矫形术后躯干呈轻度前屈为最佳。
