The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the K...The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the Kármán vortex street is observed in one component, while ‘the half-quantum vortex street' is observed in the other component. Other patterns of vortex shedding, such as oblique vortex dipoles, V-shaped vortex pairs, irregular turbulence, and combined modes of various wakes, can also be found. The ratio of inter-vortex spacing in one row to the distance between vortex rows is approximately0.18, which is less than the stability condition 0.28 of classical fluid. The drag force acting on the obstacle potential is simulated. The parametric regions of Kármán vortex street and other vortex patterns are calculated. The range of Kármán vortex street is surrounded by the region of combined modes. In addition, spin–orbit coupling disrupts the symmetry of the system and the gain-loss affects the local particle distribution of the system, which leads to the local symmetry breaking of the system, and finally influences the stability of the Kármán vortex street. Finally, we propose an experimental protocol to realize the Kármán vortex street in a system.展开更多
BACKGROUND The use of uncemented cups during total hip arthroplasty(THA)has gained popularity in recent years.The Robert Mathys(RM)pressfit cup,an uncemented monoblock implant is expected to preserve bone density due ...BACKGROUND The use of uncemented cups during total hip arthroplasty(THA)has gained popularity in recent years.The Robert Mathys(RM)pressfit cup,an uncemented monoblock implant is expected to preserve bone density due to its composition and external surface,while reducing backside wear with its monoblock construction.These factors should lead to a high survival rate of the implant.AIM To evaluate the mid-term survival and functional outcome of the RM Pressfit cup in a large study population.METHODS Between 2011 and 2020,we included 1324 patients receiving a primary THA using the RM pressfit cup.Final clinical follow-up was performed at 2 years postoperatively with the Dutch arthroplasty register used to assess implant status thereafter.Revision for acetabular failure and reason for revision were reported to evaluate implant survival,while the hip disability and osteoarthritis outcome score(HOOS)scores were used to assess functional outcome.RESULTS The mean age at surgery was 64.9 years.The mean follow-up was 4.6 years.Of the 1324 THAs performed,13 needed cup revisions within 5 years after index THA:5 due to aseptic loosening,6 due to infection,2 due to dislocation and 2 due to other causes.This resulted in a 5-year cup survival of 98.8%(95%CI:98.1-99.5).Nine of the cup revisions occurred within the first year after index THA.HOOS scores increased significantly in all domains during the first year and levelled out during the second year.CONCLUSION In the present study,the RM pressfit cup demonstrated excellent clinical outcomes at mid-term follow-up;however,future studies are needed to assess the long-term outcomes of this acetabular implant.展开更多
随着国际海事卫星通信系统(international maritime satellite communication system,INMARSAT)的不断发展,卫星地面站(satellite earth station,SES)的可用性评估具有重要意义。首先选取可靠性、维修性和保障性为指标,构建可靠性、维...随着国际海事卫星通信系统(international maritime satellite communication system,INMARSAT)的不断发展,卫星地面站(satellite earth station,SES)的可用性评估具有重要意义。首先选取可靠性、维修性和保障性为指标,构建可靠性、维修性与保障性(reliability,maintainability and supportability,RMS)模型进行SES可用性评估;其次,以SES设备为研究对象,根据马尔可夫链得到设备有效性概率,并进一步推导出系统可靠性;然后,建立排队图解协调技术(queue-graphical evaluation and review technique,Q-GERT)网络以描述SES设备的维修保障过程,并基于AnyLogic软件进行建模仿真;最后,通过算例进行应用研究,基于RMS模型进行SES可用性评估,验证了该模型和评估方法的有效性与实用性。展开更多
基金supported by the National Key R&D Program of China[grant number 2022YFF0801301]the National Natural Science Foundation of China[grant number 41575033]+1 种基金the Fengyun Satellite Application Pioneer Project[grant number FY-APP-2022.0111]the Natural Science Foundation of Jiangsu Province[grant number BK20231148]。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12065022 and 12147213)。
文摘The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the Kármán vortex street is observed in one component, while ‘the half-quantum vortex street' is observed in the other component. Other patterns of vortex shedding, such as oblique vortex dipoles, V-shaped vortex pairs, irregular turbulence, and combined modes of various wakes, can also be found. The ratio of inter-vortex spacing in one row to the distance between vortex rows is approximately0.18, which is less than the stability condition 0.28 of classical fluid. The drag force acting on the obstacle potential is simulated. The parametric regions of Kármán vortex street and other vortex patterns are calculated. The range of Kármán vortex street is surrounded by the region of combined modes. In addition, spin–orbit coupling disrupts the symmetry of the system and the gain-loss affects the local particle distribution of the system, which leads to the local symmetry breaking of the system, and finally influences the stability of the Kármán vortex street. Finally, we propose an experimental protocol to realize the Kármán vortex street in a system.
文摘BACKGROUND The use of uncemented cups during total hip arthroplasty(THA)has gained popularity in recent years.The Robert Mathys(RM)pressfit cup,an uncemented monoblock implant is expected to preserve bone density due to its composition and external surface,while reducing backside wear with its monoblock construction.These factors should lead to a high survival rate of the implant.AIM To evaluate the mid-term survival and functional outcome of the RM Pressfit cup in a large study population.METHODS Between 2011 and 2020,we included 1324 patients receiving a primary THA using the RM pressfit cup.Final clinical follow-up was performed at 2 years postoperatively with the Dutch arthroplasty register used to assess implant status thereafter.Revision for acetabular failure and reason for revision were reported to evaluate implant survival,while the hip disability and osteoarthritis outcome score(HOOS)scores were used to assess functional outcome.RESULTS The mean age at surgery was 64.9 years.The mean follow-up was 4.6 years.Of the 1324 THAs performed,13 needed cup revisions within 5 years after index THA:5 due to aseptic loosening,6 due to infection,2 due to dislocation and 2 due to other causes.This resulted in a 5-year cup survival of 98.8%(95%CI:98.1-99.5).Nine of the cup revisions occurred within the first year after index THA.HOOS scores increased significantly in all domains during the first year and levelled out during the second year.CONCLUSION In the present study,the RM pressfit cup demonstrated excellent clinical outcomes at mid-term follow-up;however,future studies are needed to assess the long-term outcomes of this acetabular implant.
文摘随着国际海事卫星通信系统(international maritime satellite communication system,INMARSAT)的不断发展,卫星地面站(satellite earth station,SES)的可用性评估具有重要意义。首先选取可靠性、维修性和保障性为指标,构建可靠性、维修性与保障性(reliability,maintainability and supportability,RMS)模型进行SES可用性评估;其次,以SES设备为研究对象,根据马尔可夫链得到设备有效性概率,并进一步推导出系统可靠性;然后,建立排队图解协调技术(queue-graphical evaluation and review technique,Q-GERT)网络以描述SES设备的维修保障过程,并基于AnyLogic软件进行建模仿真;最后,通过算例进行应用研究,基于RMS模型进行SES可用性评估,验证了该模型和评估方法的有效性与实用性。
