To improve the characteristics of wet multi-disc brakes (WMDBs), the WMDBs of the drive axles of mining trucks were studied. A model was established to predict the phenomenon of drag characteristics during wet brake n...To improve the characteristics of wet multi-disc brakes (WMDBs), the WMDBs of the drive axles of mining trucks were studied. A model was established to predict the phenomenon of drag characteristics during wet brake non-engagement by considering the combined effect of surface grooves, film shrinkage, and laminar Navier-Stokes (N-S) equations. The model was used to study drag torque and temperature variation of the wet brakes for different volume flows, dynamic viscosities, and friction pair clearances. The simulation results indicated that the peak torque decreased when the clearance of the friction pair increased. Additionally, the peak torque increased when the volume flow increased and when the cooling liquid dynamic viscosity increased. The model was more accurate than a traditional forecasting system when considering the role of surface grooves and oil film shrinkage in actual working conditions.展开更多
目的评估基于多参数磁共振的膀胱影像-报告和数据系统(vesical imaging-reporting and data system,VI-RADS)对膀胱癌肌层浸润与否的诊断预测价值。方法收集重庆大学附属肿瘤医院2017年1月至2021年3月行多参数磁共振检查并完成经尿道膀...目的评估基于多参数磁共振的膀胱影像-报告和数据系统(vesical imaging-reporting and data system,VI-RADS)对膀胱癌肌层浸润与否的诊断预测价值。方法收集重庆大学附属肿瘤医院2017年1月至2021年3月行多参数磁共振检查并完成经尿道膀胱肿瘤切除术(transurethral resection of bladder tumor,TURBT)或根治性膀胱切除术的278例膀胱病变患者临床资料;不同影像学医师分别进行磁共振VI-RADS评分,Kappa检验其一致性;分析VI-RADS评分与病理结果的吻合度;采用受试者工作特征曲线(receiver operating characteristic curve,ROC)分析VI-RADS各评分诊断肌层浸润性膀胱癌的效能;比较不同手术方式获取的病理组织与VI-RADS评分吻合度。结果两位影像评估者VI-RADS评分一致性较好(符合率为79.86%,Kappa值=0.7508,P<0.001)。ROC曲线分析显示,VI-RADS评分≥3时预测肌层浸润性膀胱癌的曲线下面积为0.774,约登指数为54.78%,敏感度为96.16%,特异度为58.62%,阳性预测值(positive predictive value,PPV)为58.14%,阴性预测值(negative predictive value,NPV)为96.23%。根治性膀胱切除术获得的病理结果与VI-RADS评分吻合度高达92.85%,显著高于行TURBT术的79.81%(P<0.05)。结论术前多参数磁共振VI-RADS评分具有良好的一致性和稳定性,与术后病理吻合度高;VI-RADS评分≥3分对肌层浸润性膀胱癌的预测价值较好,可指导临床手术选择方式。展开更多
基金Supported by the National Natural Science Foundation of China(51375519)the Chongqing Graduate Education Innovation Fund Project(CYS18223)the Chongqing University of Arts and Sciences Graduate School Research Project(M2018ME16)
文摘To improve the characteristics of wet multi-disc brakes (WMDBs), the WMDBs of the drive axles of mining trucks were studied. A model was established to predict the phenomenon of drag characteristics during wet brake non-engagement by considering the combined effect of surface grooves, film shrinkage, and laminar Navier-Stokes (N-S) equations. The model was used to study drag torque and temperature variation of the wet brakes for different volume flows, dynamic viscosities, and friction pair clearances. The simulation results indicated that the peak torque decreased when the clearance of the friction pair increased. Additionally, the peak torque increased when the volume flow increased and when the cooling liquid dynamic viscosity increased. The model was more accurate than a traditional forecasting system when considering the role of surface grooves and oil film shrinkage in actual working conditions.
