By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter （micro ADV） was used to measure local flow...By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter （micro ADV） was used to measure local flow velocities and Reynolds stress. The results show that hydraulic characteristics in non-vegetation and vegetation layers are totally different. In a region above the vegetation, Reynolds stress distribution is linear, and the measured velocity profile is a classical logarithmic one. Based on the concept of new-riverbed, the river compression parameter representing the impact of vegetation on river is given, and a new assumption of mixing length expression is made. The formula for time-averaged velocity derived from the expression requires less parameters and simple calculation, and is useful in applications.展开更多
How can teachers teach English writing effectively? And how can students learn to write essays correctly? These seem to be two puzzling problems for Chinese teachers and learners.This paper aims to introduce a new tea...How can teachers teach English writing effectively? And how can students learn to write essays correctly? These seem to be two puzzling problems for Chinese teachers and learners.This paper aims to introduce a new teaching approach:the Length Approach,and discusses its merits.展开更多
[目的]探讨Mako机器人辅助经改良Harding入路全髋关节置换术(total hip arthroplasty,THA)的治疗效果及安全性。[方法]回顾性分析本院2021年4月—2023年5月行THA的48例患者的资料。根据手术前医患沟通结果,24例采用Mako机器人辅助下THA...[目的]探讨Mako机器人辅助经改良Harding入路全髋关节置换术(total hip arthroplasty,THA)的治疗效果及安全性。[方法]回顾性分析本院2021年4月—2023年5月行THA的48例患者的资料。根据手术前医患沟通结果,24例采用Mako机器人辅助下THA(机器人组),另外24例采用经改良Harding入路常规徒手THA(徒手组)。比较两组患者围手术期、随访结果及影像评估资料。[结果]两组患者均顺利完成改良Harding入路THA,机器人组的手术时间[min,(102.6±15.7)vs(83.7±16.8),P<0.001]和术中出血量[mL,(279.7±35.1)vs(212.5±29.6),P<0.001]均显著大于徒手组,两组患者术后引流量、住院天数的差异无统计学意义(P>0.05)。术后平均随访(20.8±8.5)个月。随时间推移,两组患者VAS评分、Harris评分、最大伸髋和最大屈髋活动度(range of motion,ROM)、最大内收和最大外展ROM均显著改善(P<0.05)。术后1周机器人组的VAS评分[分,M(P25,P75),2.0(2.0,4.0)vs 3.5(3.0,5.0),P<0.001]、最大屈髋[°,(74.5±9.0)vs(66.5±10.4),P=0.006]、最大内收[°,(18.5±6.2)vs(7.0±1.6),P<0.001]显著优于徒手组;术后1周和术后3个月机器人组的Harris评分[分,(75.1±4.9)vs(68.3±5.1),P<0.001;(84.8±4.9)vs(78.3±4.5),P<0.001]、最大伸髋[°,(20.5±5.3)vs(12.5±5.6),P<0.001;(31.0±3.6)vs(24.1±4.5),P<0.001]、最大外展[°,(26.2±3.3)vs(21.5±4.8),P<0.001;(33.4±3.8)vs(27.8±4.3),P<0.001]显著优于徒手组,但是,末次随访时两组间上述指标的差异均已无统计学意义(P>0.05)。影像方面,机器人组的术后双下肢长度差异(leg length discrepancy,LLD)[mm,(4.9±1.0)vs(8.1±1.4),P<0.001]和双侧联合偏心距(combined offset,CO)差值(■CO)的绝对值[mm,(1.5±0.5)vs(3.5±0.6),P<0.001]、髋臼假体外展角[°,(40.3±1.7)vs(45.3±4.1),P<0.001]和前倾角[°,(15.9±1.2)vs(18.8±3.6),P<0.001]均显著小于徒手组。[结论]与常规徒手THA相比,Mako机器人辅助下改良Harding入路THA假体置放更精准,早期治疗效果更优,但机器人技术的手术时间较长且术中失血量更大。展开更多
基金supported by the National Natural Science Foundation of China (Nos. 50679061, 50709025,50749031)
文摘By choosing a PVC slice to simulate flexible vegetation, we carried out experiments in an open channel with submerged flexible vegetation. A 3D acoustic Doppler velocimeter （micro ADV） was used to measure local flow velocities and Reynolds stress. The results show that hydraulic characteristics in non-vegetation and vegetation layers are totally different. In a region above the vegetation, Reynolds stress distribution is linear, and the measured velocity profile is a classical logarithmic one. Based on the concept of new-riverbed, the river compression parameter representing the impact of vegetation on river is given, and a new assumption of mixing length expression is made. The formula for time-averaged velocity derived from the expression requires less parameters and simple calculation, and is useful in applications.
文摘How can teachers teach English writing effectively? And how can students learn to write essays correctly? These seem to be two puzzling problems for Chinese teachers and learners.This paper aims to introduce a new teaching approach:the Length Approach,and discusses its merits.
文摘[目的]探讨Mako机器人辅助经改良Harding入路全髋关节置换术(total hip arthroplasty,THA)的治疗效果及安全性。[方法]回顾性分析本院2021年4月—2023年5月行THA的48例患者的资料。根据手术前医患沟通结果,24例采用Mako机器人辅助下THA(机器人组),另外24例采用经改良Harding入路常规徒手THA(徒手组)。比较两组患者围手术期、随访结果及影像评估资料。[结果]两组患者均顺利完成改良Harding入路THA,机器人组的手术时间[min,(102.6±15.7)vs(83.7±16.8),P<0.001]和术中出血量[mL,(279.7±35.1)vs(212.5±29.6),P<0.001]均显著大于徒手组,两组患者术后引流量、住院天数的差异无统计学意义(P>0.05)。术后平均随访(20.8±8.5)个月。随时间推移,两组患者VAS评分、Harris评分、最大伸髋和最大屈髋活动度(range of motion,ROM)、最大内收和最大外展ROM均显著改善(P<0.05)。术后1周机器人组的VAS评分[分,M(P25,P75),2.0(2.0,4.0)vs 3.5(3.0,5.0),P<0.001]、最大屈髋[°,(74.5±9.0)vs(66.5±10.4),P=0.006]、最大内收[°,(18.5±6.2)vs(7.0±1.6),P<0.001]显著优于徒手组;术后1周和术后3个月机器人组的Harris评分[分,(75.1±4.9)vs(68.3±5.1),P<0.001;(84.8±4.9)vs(78.3±4.5),P<0.001]、最大伸髋[°,(20.5±5.3)vs(12.5±5.6),P<0.001;(31.0±3.6)vs(24.1±4.5),P<0.001]、最大外展[°,(26.2±3.3)vs(21.5±4.8),P<0.001;(33.4±3.8)vs(27.8±4.3),P<0.001]显著优于徒手组,但是,末次随访时两组间上述指标的差异均已无统计学意义(P>0.05)。影像方面,机器人组的术后双下肢长度差异(leg length discrepancy,LLD)[mm,(4.9±1.0)vs(8.1±1.4),P<0.001]和双侧联合偏心距(combined offset,CO)差值(■CO)的绝对值[mm,(1.5±0.5)vs(3.5±0.6),P<0.001]、髋臼假体外展角[°,(40.3±1.7)vs(45.3±4.1),P<0.001]和前倾角[°,(15.9±1.2)vs(18.8±3.6),P<0.001]均显著小于徒手组。[结论]与常规徒手THA相比,Mako机器人辅助下改良Harding入路THA假体置放更精准,早期治疗效果更优,但机器人技术的手术时间较长且术中失血量更大。
