The safety and stability of high-speed maglev trains traveling on viaducts in crosswinds critically depend on their aerodynamic characteristics.Therefore,this paper uses an improved delayed detached eddy simulation(ID...The safety and stability of high-speed maglev trains traveling on viaducts in crosswinds critically depend on their aerodynamic characteristics.Therefore,this paper uses an improved delayed detached eddy simulation(IDDES)method to investigate the aerodynamic features of high-speed maglev trains with different marshaling lengths under crosswinds.The effects of marshaling lengths(varying from 3-car to 8-car groups)on the train’s aerodynamic performance,surface pressure,and the flow field surrounding the train were investigated using the three-dimensional unsteady compressible Navier-Stokes(N-S)equations.The results showed that the marshaling lengths had minimal influence on the aerodynamic performance of the head and middle cars.Conversely,the marshaling lengths are negatively correlated with the time-average side force coefficient(CS)and time-average lift force coefficient(Cl)of the tail car.Compared to the tail car of the 3-car groups,the CS and Cl fell by 27.77%and 18.29%,respectively,for the tail car of the 8-car groups.It is essential to pay more attention to the operational safety of the head car,as it exhibits the highest time average CS.Additionally,the mean pressure difference between the two sides of the tail car body increased with the marshaling lengths,and the side force direction on the tail car was opposite to that of the head and middle cars.Furthermore,the turbulent kinetic energy of the wake structure on the windward side quickly decreased as marshaling lengths increased.展开更多
To study the influence of the speed-up of a freight train with mixed marshaling of light and heavy vehicles on the dynamic behavior,a dynamic model of the freight train was established based on the modular method of c...To study the influence of the speed-up of a freight train with mixed marshaling of light and heavy vehicles on the dynamic behavior,a dynamic model of the freight train was established based on the modular method of cyclic variables,and the dynamic behavior of the freight train was simulated and analyzed under different marshaling patterns,speeds and line conditions.On-site speed-up test with different marshaling freight trains was carried out,and the stability and ride-index of the train before and after the speed-up were compared and analyzed.The feasibility of increasing the speed of freight trains with mixed marshaling of light and heavy cars was demonstrated theoretically and experimentally.The results show that the theory is in good agreement with the test,which can effectively reflect the dynamic behavior of the vehicle.The dynamic behavior of the freight train in the study meets the requirements of increasing speed to 90 km/h.This paper provides a theoretical basis and method for railway freight transportation and the speed-up of freight vehicles.展开更多
Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model o...Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model of system operation division of labor based on resource constraint is constructed. The model is solved by using genetic algorithm, and the improving strategy for solving the model is proposed. The application example indicates that the model and algorithm can effectively solve the problem of operation division of labor at two-way marshaling station.展开更多
目的:评价持续性心房颤动患者“2C3L”联合Marshall静脉(vein of Marshall,VOM)无水乙醇化学消融术式的有效性及其影响因素。方法:选取2019年7月至2022年5月,在首都医科大学附属北京安贞医院心律失常中心行首次心房颤动射频消融术,应用...目的:评价持续性心房颤动患者“2C3L”联合Marshall静脉(vein of Marshall,VOM)无水乙醇化学消融术式的有效性及其影响因素。方法:选取2019年7月至2022年5月,在首都医科大学附属北京安贞医院心律失常中心行首次心房颤动射频消融术,应用“2C3L”联合Marshall静脉乙醇消融(“改良2C3L”术式)的心房颤动患者,分析该手术策略的1年心房颤动复发及复发影响因素。“改良2C3L”术式具体为:VOM无水乙醇化学消融;“2C3L”消融,即双侧环肺静脉消融、二尖瓣峡部线消融及冠状静脉内消融、左心房顶部线消融、三尖瓣峡部线消融;窦性心律下验证肺静脉隔离及消融径线传导阻滞。结果:该策略消融术304例,随访1年复发率为20.3%(n=62),冠状动脉粥样硬化性心脏病(OR=3.15,95%CI:1.27~7.65)、心房颤动持续时间(OR=1.11,95%CI:1.06~1.16)以及吸烟(OR=2.59,95%CI:1.00~6.50)为影响术后1年复发的危险因素。结论:“改良2C3L”术式可有效实现持续心房颤动患者的节律控制。展开更多
目的:探讨可控弯鞘在马歇尔静脉(vein of Marshall,VoM)无水乙醇化学消融(ethanol infusion in the vein of Marshall,EIVOM)中的临床应用策略。方法:纳入2023年1月至2023年12月期间于北京安贞医院接受EIVOM治疗的心房颤动患者191例,术...目的:探讨可控弯鞘在马歇尔静脉(vein of Marshall,VoM)无水乙醇化学消融(ethanol infusion in the vein of Marshall,EIVOM)中的临床应用策略。方法:纳入2023年1月至2023年12月期间于北京安贞医院接受EIVOM治疗的心房颤动患者191例,术中全部首选固定弯长鞘行EIVOM,其中26例进一步应用可控弯鞘。据此将患者分为固定弯鞘组(n=165)以及可控弯鞘组(n=26),对比两组患者的临床基线资料、术中资料以及EIVOM相关并发症。结果:纳入的191例患者平均年龄(61.8±10.1)岁,其中男性111例(58.1%),两组患者临床基线资料差异无统计学意义。经过术中资料对比,可控弯鞘组的26例患者中,15例患者出现三尖瓣峡部偏长(38.0±1.1)mm、10例患者的Marshall静脉开口在右前斜30°下距离冠状窦口较近(7.7±0.9)mm、7例患者出现欧氏嵴偏高(12.4±1.0)mm;全部191例患者中,3例患者EIVOM治疗未成功,两组患者均未出现并发症。结论:在Marshall静脉无水乙醇化学消融时,三尖瓣峡部偏长、Marshall静脉开口较近、欧氏嵴偏高等情况应用可控弯鞘有助于消融的操作且不会增加并发症的发生率。展开更多
目的通过Web of Science(WOS)数据库检索2000~2023年Marshall静脉(VOM)相关文献,对文献总结并进行可视化分析,研究该领域的发展现状。方法以WOS中核心合集拓展数据库为数据来源,收录2000年至2023年相关文献并运用R软件执行描述性文献计...目的通过Web of Science(WOS)数据库检索2000~2023年Marshall静脉(VOM)相关文献,对文献总结并进行可视化分析,研究该领域的发展现状。方法以WOS中核心合集拓展数据库为数据来源,收录2000年至2023年相关文献并运用R软件执行描述性文献计量分析,以及利用CiteSpace,VOSviewer等软件工具进行可视化结果解释。结果检索获得共145篇文献,由来自17个国家227个研究机构的816位研究者在34种期刊上发表。从2000年开始发文量持续增加,特别是从2019年以来发文量呈现出爆发性增长。美国不仅在发文量以及文献被引数上均表现出主导地位,而且加利福尼亚大学洛杉矶分校(University of California,Los Angeles)以最多的总引用次数(587次)被认为是最活跃的研究机构,JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY的年发表论文数量最高,且总本地引用次数也最多。研究者Duchateau是近年来在该领域最活跃的研究者之一,Hwang则是该领域最早,也是最有影响力的研究者之一。时间线研究发现“二尖瓣峡部消融”是最重要的研究领域,且近几年以持续性房颤和无水乙醇灌注消融为最热门的研究方向。结论应用文献计量分析法分析VOM相关文献,全面且直观地展示了该领域的研究热点和研究方向,为进一步研究提供有效的参考信息。展开更多
目的 旨在评估快速交换球囊技术应用于Marshall静脉(vein of Marshall, VOM)无水酒精消融术中的安全性与可行性。方法 回顾性分析2024年2月至2024年8月就诊于河南省人民医院首次行射频消融术及VOM无水酒精消融的48例持续性房颤患者的临...目的 旨在评估快速交换球囊技术应用于Marshall静脉(vein of Marshall, VOM)无水酒精消融术中的安全性与可行性。方法 回顾性分析2024年2月至2024年8月就诊于河南省人民医院首次行射频消融术及VOM无水酒精消融的48例持续性房颤患者的临床资料。依据VOM无水酒精消融过程中球囊封堵方法的差异,将患者分为整体交换(over the wire, OTW)球囊组(26例)与快速交换球囊组(22例)。对比两组患者术中二尖瓣峡部阻断率、二尖瓣峡部总消融时间、球囊封堵时间、总手术时间、X线透视时间以及手术相关并发症的发生情况。结果 两组患者的二尖瓣峡部阻断率、二尖瓣峡部总消融时间以及总手术时间比较差异无统计学意义(P>0.05)。相比于OTW球囊组,快速交换球囊组的球囊封堵时间减少[10.00(9.00,12.25) min vs 11.50(10.00,15.00) min,Z=-2.211,P=0.027]、X线透视时间降低[8.50(7.75,9.25) min vs 9.50(8.00,10.25)min,Z=-2.099,P=0.036]。两组患者术后均未出现严重并发症。结论 快速交换球囊技术应用于VOM无水酒精消融术具备安全性与可行性,值得临床推广应用。展开更多
心房颤动(以下简称房颤)是临床上最常见的心律失常之一,持续性心房颤动(PsAF)的导管消融治疗一直是临床上的挑战。PsAF消融以肺静脉隔离为基石,但单纯肺静脉隔离治疗效果有限。近年来房颤消融策略不断优化,并在临床试验中取得良好的疗效...心房颤动(以下简称房颤)是临床上最常见的心律失常之一,持续性心房颤动(PsAF)的导管消融治疗一直是临床上的挑战。PsAF消融以肺静脉隔离为基石,但单纯肺静脉隔离治疗效果有限。近年来房颤消融策略不断优化,并在临床试验中取得良好的疗效,其中Marshall静脉(VOM)无水乙醇消融作为一种新兴技术,展现出独特的优势和应用前景,多项临床研究证实了其安全性和有效性。 Atrial fibrillation is one of the most common arrhythmias in clinical practice, and catheter ablation therapy for persistent atrial fibrillation (PsAF) has been a clinical challenge. PsAF ablation therapy is based on pulmonary vein isolation as a cornerstone, but pulmonary vein isolation alone has limited efficacy. Atrial fibrillation ablation strategies have been optimised in recent years and have shown promising results in clinical trials. Among them, vein of Marshall (Vein of Marshall, VOM) alcohol ablation, as an emerging technology, shows unique advantages and application prospects.展开更多
基金supported by Wuyi University Hong Kong and Macao Joint Research and Development Fund(GrantsNos.2021WGALH15,2019WGALH17,2019WGALH15)the National Natural Science Foundation of China-Guangdong Joint Fund(GrantsNo.2019A1515111052)+2 种基金the National Natural Science Foundation of China(Grant No.52202426)a grant from the Research Grants Council(RGC)of the Hong Kong Special Administrative Region(SAR),China(Grants No.15205723)a grant from the Hong Kong Polytechnic University(Grant No.P0045325).
文摘The safety and stability of high-speed maglev trains traveling on viaducts in crosswinds critically depend on their aerodynamic characteristics.Therefore,this paper uses an improved delayed detached eddy simulation(IDDES)method to investigate the aerodynamic features of high-speed maglev trains with different marshaling lengths under crosswinds.The effects of marshaling lengths(varying from 3-car to 8-car groups)on the train’s aerodynamic performance,surface pressure,and the flow field surrounding the train were investigated using the three-dimensional unsteady compressible Navier-Stokes(N-S)equations.The results showed that the marshaling lengths had minimal influence on the aerodynamic performance of the head and middle cars.Conversely,the marshaling lengths are negatively correlated with the time-average side force coefficient(CS)and time-average lift force coefficient(Cl)of the tail car.Compared to the tail car of the 3-car groups,the CS and Cl fell by 27.77%and 18.29%,respectively,for the tail car of the 8-car groups.It is essential to pay more attention to the operational safety of the head car,as it exhibits the highest time average CS.Additionally,the mean pressure difference between the two sides of the tail car body increased with the marshaling lengths,and the side force direction on the tail car was opposite to that of the head and middle cars.Furthermore,the turbulent kinetic energy of the wake structure on the windward side quickly decreased as marshaling lengths increased.
基金The authors gratefully acknowledge the support of the School-enterprise cooperation projects(No.20200203)。
文摘To study the influence of the speed-up of a freight train with mixed marshaling of light and heavy vehicles on the dynamic behavior,a dynamic model of the freight train was established based on the modular method of cyclic variables,and the dynamic behavior of the freight train was simulated and analyzed under different marshaling patterns,speeds and line conditions.On-site speed-up test with different marshaling freight trains was carried out,and the stability and ride-index of the train before and after the speed-up were compared and analyzed.The feasibility of increasing the speed of freight trains with mixed marshaling of light and heavy cars was demonstrated theoretically and experimentally.The results show that the theory is in good agreement with the test,which can effectively reflect the dynamic behavior of the vehicle.The dynamic behavior of the freight train in the study meets the requirements of increasing speed to 90 km/h.This paper provides a theoretical basis and method for railway freight transportation and the speed-up of freight vehicles.
文摘Based on the systematic analysis of the operation process at two-way marshaling station, the operation ways of through car flows, sorting car flows and loading car flows are comprehensively studied. An optimal model of system operation division of labor based on resource constraint is constructed. The model is solved by using genetic algorithm, and the improving strategy for solving the model is proposed. The application example indicates that the model and algorithm can effectively solve the problem of operation division of labor at two-way marshaling station.
文摘目的:评价持续性心房颤动患者“2C3L”联合Marshall静脉(vein of Marshall,VOM)无水乙醇化学消融术式的有效性及其影响因素。方法:选取2019年7月至2022年5月,在首都医科大学附属北京安贞医院心律失常中心行首次心房颤动射频消融术,应用“2C3L”联合Marshall静脉乙醇消融(“改良2C3L”术式)的心房颤动患者,分析该手术策略的1年心房颤动复发及复发影响因素。“改良2C3L”术式具体为:VOM无水乙醇化学消融;“2C3L”消融,即双侧环肺静脉消融、二尖瓣峡部线消融及冠状静脉内消融、左心房顶部线消融、三尖瓣峡部线消融;窦性心律下验证肺静脉隔离及消融径线传导阻滞。结果:该策略消融术304例,随访1年复发率为20.3%(n=62),冠状动脉粥样硬化性心脏病(OR=3.15,95%CI:1.27~7.65)、心房颤动持续时间(OR=1.11,95%CI:1.06~1.16)以及吸烟(OR=2.59,95%CI:1.00~6.50)为影响术后1年复发的危险因素。结论:“改良2C3L”术式可有效实现持续心房颤动患者的节律控制。
文摘目的:探讨可控弯鞘在马歇尔静脉(vein of Marshall,VoM)无水乙醇化学消融(ethanol infusion in the vein of Marshall,EIVOM)中的临床应用策略。方法:纳入2023年1月至2023年12月期间于北京安贞医院接受EIVOM治疗的心房颤动患者191例,术中全部首选固定弯长鞘行EIVOM,其中26例进一步应用可控弯鞘。据此将患者分为固定弯鞘组(n=165)以及可控弯鞘组(n=26),对比两组患者的临床基线资料、术中资料以及EIVOM相关并发症。结果:纳入的191例患者平均年龄(61.8±10.1)岁,其中男性111例(58.1%),两组患者临床基线资料差异无统计学意义。经过术中资料对比,可控弯鞘组的26例患者中,15例患者出现三尖瓣峡部偏长(38.0±1.1)mm、10例患者的Marshall静脉开口在右前斜30°下距离冠状窦口较近(7.7±0.9)mm、7例患者出现欧氏嵴偏高(12.4±1.0)mm;全部191例患者中,3例患者EIVOM治疗未成功,两组患者均未出现并发症。结论:在Marshall静脉无水乙醇化学消融时,三尖瓣峡部偏长、Marshall静脉开口较近、欧氏嵴偏高等情况应用可控弯鞘有助于消融的操作且不会增加并发症的发生率。
文摘目的通过Web of Science(WOS)数据库检索2000~2023年Marshall静脉(VOM)相关文献,对文献总结并进行可视化分析,研究该领域的发展现状。方法以WOS中核心合集拓展数据库为数据来源,收录2000年至2023年相关文献并运用R软件执行描述性文献计量分析,以及利用CiteSpace,VOSviewer等软件工具进行可视化结果解释。结果检索获得共145篇文献,由来自17个国家227个研究机构的816位研究者在34种期刊上发表。从2000年开始发文量持续增加,特别是从2019年以来发文量呈现出爆发性增长。美国不仅在发文量以及文献被引数上均表现出主导地位,而且加利福尼亚大学洛杉矶分校(University of California,Los Angeles)以最多的总引用次数(587次)被认为是最活跃的研究机构,JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY的年发表论文数量最高,且总本地引用次数也最多。研究者Duchateau是近年来在该领域最活跃的研究者之一,Hwang则是该领域最早,也是最有影响力的研究者之一。时间线研究发现“二尖瓣峡部消融”是最重要的研究领域,且近几年以持续性房颤和无水乙醇灌注消融为最热门的研究方向。结论应用文献计量分析法分析VOM相关文献,全面且直观地展示了该领域的研究热点和研究方向,为进一步研究提供有效的参考信息。
文摘目的 旨在评估快速交换球囊技术应用于Marshall静脉(vein of Marshall, VOM)无水酒精消融术中的安全性与可行性。方法 回顾性分析2024年2月至2024年8月就诊于河南省人民医院首次行射频消融术及VOM无水酒精消融的48例持续性房颤患者的临床资料。依据VOM无水酒精消融过程中球囊封堵方法的差异,将患者分为整体交换(over the wire, OTW)球囊组(26例)与快速交换球囊组(22例)。对比两组患者术中二尖瓣峡部阻断率、二尖瓣峡部总消融时间、球囊封堵时间、总手术时间、X线透视时间以及手术相关并发症的发生情况。结果 两组患者的二尖瓣峡部阻断率、二尖瓣峡部总消融时间以及总手术时间比较差异无统计学意义(P>0.05)。相比于OTW球囊组,快速交换球囊组的球囊封堵时间减少[10.00(9.00,12.25) min vs 11.50(10.00,15.00) min,Z=-2.211,P=0.027]、X线透视时间降低[8.50(7.75,9.25) min vs 9.50(8.00,10.25)min,Z=-2.099,P=0.036]。两组患者术后均未出现严重并发症。结论 快速交换球囊技术应用于VOM无水酒精消融术具备安全性与可行性,值得临床推广应用。
文摘心房颤动(以下简称房颤)是临床上最常见的心律失常之一,持续性心房颤动(PsAF)的导管消融治疗一直是临床上的挑战。PsAF消融以肺静脉隔离为基石,但单纯肺静脉隔离治疗效果有限。近年来房颤消融策略不断优化,并在临床试验中取得良好的疗效,其中Marshall静脉(VOM)无水乙醇消融作为一种新兴技术,展现出独特的优势和应用前景,多项临床研究证实了其安全性和有效性。 Atrial fibrillation is one of the most common arrhythmias in clinical practice, and catheter ablation therapy for persistent atrial fibrillation (PsAF) has been a clinical challenge. PsAF ablation therapy is based on pulmonary vein isolation as a cornerstone, but pulmonary vein isolation alone has limited efficacy. Atrial fibrillation ablation strategies have been optimised in recent years and have shown promising results in clinical trials. Among them, vein of Marshall (Vein of Marshall, VOM) alcohol ablation, as an emerging technology, shows unique advantages and application prospects.
