[目的]比较关节镜下缝合钩和Fast-fix缝合Ⅳ型半月板Ramp区损伤的临床疗效。[方法]回顾性分析2016年1月—2020年10月45例前交叉韧带(anterior cruciate ligament, ACL)损伤合并Ⅳ型半月板Ramp损伤患者的临床资料。所有患者均取自体腘绳...[目的]比较关节镜下缝合钩和Fast-fix缝合Ⅳ型半月板Ramp区损伤的临床疗效。[方法]回顾性分析2016年1月—2020年10月45例前交叉韧带(anterior cruciate ligament, ACL)损伤合并Ⅳ型半月板Ramp损伤患者的临床资料。所有患者均取自体腘绳肌腱行ACL重建,依据术前医患沟通结果,21例应用缝合钩缝合Ramp损伤,24例应用Fast-fix缝合。对比患者围手术期、随访及影像学结果。[结果]所有患者均顺利完成手术,术中未出现血管、神经损伤等并发症。缝合钩组手术时间[(91.2±10.6) min vs (62.5±8.4) min, P<0.001]、切口总长度[(5.9±0.5) cm vs (5.1±0.6) cm, P<0.001]均显著长于Fast-fix组,但前者住院费用显著少于后者[(3.4±0.3)万元vs (4.3±0.7)万元, P<0.001]。两组Ramp撕裂长度、缝合针数、下地行走时间、切口愈合、住院时间比较差异均无统计学意义(P>0.05)。所有患者均获36~72个月随访。两组完全负重活动时间的差异无统计学意义(P>0.05)。术后1年及末次随访时,两组膝间隙压痛、麦氏征,轴移征、膝关节屈伸ROM、IKDC评分及Lysholm评分较术前均显著改善(P<0.05)。同一时间点,两组上述指标的差异均无统计学意义(P>0.05)。影像方面,与术前相比,术后1年,两组半月板损伤分级及胫骨平台后侧骨髓水肿均显著改善(P<0.05),相应时间点,两组上述指标的差异均无统计学意义(P>0.05)。术后1年MRI显示缝合钩组愈合率为90.5%、Fast-fix组为87.5%,差异无统计学意义(P>0.05)。[结论]关节镜下缝合钩和Fast-fix缝合半月板Ramp区Ⅳ型损伤均可获得满意疗效。展开更多
The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this pape...The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this paper constructs a transient rolling contact finite element model of the wheel-rail in switch under different ramps using ANSYS/LSDYNA method,and analyzes the tribology and damage characteristics when the wheel passes through the switch at a uniform speed.Our research findings reveal that the vibration induced in the switch rail during the wheel load transfer process leads to a step-like increase in the contact force.Moreover,the interaction between the wheel and the rail primarily involves slip contact,which may significantly contribute to the formation of corrugations on the switch rail.Additionally,the presence of large ramps exacerbates switch rail wear and rolling contact fatigue,resulting in a notable 13.2%increase in switch rail damage under 40‰ramp conditions compared to flat(0‰ramp)conditions.Furthermore,the large ramps can alter the direction of crack propagation,ultimately causing surface spalling of the rail.Therefore,large ramps intensify the dynamic interactions during the wheel load transfer process,further aggravating the crack and spalling damage to the switch rails.展开更多
This paper represents a case study of traffic congestion within a section on Al Seeb Street highway due to the on-ramp merging of vehicles that causes a bottleneck in the mainline road. It studies the efficiency of in...This paper represents a case study of traffic congestion within a section on Al Seeb Street highway due to the on-ramp merging of vehicles that causes a bottleneck in the mainline road. It studies the efficiency of installing ramp metering within a ramp within the selected study zone. This is done by simulating the collected data using Vissim software by drawing three one-hour-long scenarios;the first scenario reflects the data collected for 30 minutes duration and is used as a base scenario to draw the other two scenarios, which are reflected as factored-up scenarios to create a situation observed in the early morning in the study zone at 6:00-7:00 in which slowing down of speeds exist, and breakdown is raised in working days. The two factoring-up scenarios were as follows: one without ramp metering and the other without ramp metering. Each scenario was calibrated and run five times with random seeds, and then the average was considered. The simulation examines the ability of RM to smooth traffic in mainline and reduce queuing on on-ramp roads within the selected study zone by comparing the performance of the network for the scenarios and comparing them in terms of the overall delays, number of stops and the average speeds for the vehicles within the mainline. The results showed a good performance reflected by the scenario with ramp metering with a reduction of the overall delay, a decrease in stops number and an increase of the average speed were achieved. For the base scenario, a visualization (video extracted from Vissim software) was extracted, showing no need to install RM with an associated table showing a number of stops equal to zero with an average speed of 102.74 km/h and a total delay of 6045 seconds. For the second scenario with no RM, a visualization was extracted showing a slowing down of speeds for vehicles within the mainline while vehicles merging from the on-ramp and need to be controlled with a table showing a number of stops equal to 16 and an average speed equal to 58 km/h and a total delay of 916,874 seconds. For the third scenario with RM, a visualization was extracted showing good control of the second scenario with a table showing the number of stops equal to 6, an average speed equal to 61 km/h and a total delay equal to 484,466 seconds. Ten literatures in regard to this study have been reviewed. The data collected are quantitative, which are collected using an indirect manual counting method and then the data is used to feed the software for simulation.展开更多
目的评价屈膝90°MRI对内侧半月板Ramp损伤的临床诊断价值。方法以2021年9月—2023年9月以膝关节疼痛为主诉收治的228例患者作为研究对象,其中51例患者符合选择标准纳入研究。男31例,女20例;年龄15~67岁,平均38.6岁。身体质量指数17...目的评价屈膝90°MRI对内侧半月板Ramp损伤的临床诊断价值。方法以2021年9月—2023年9月以膝关节疼痛为主诉收治的228例患者作为研究对象,其中51例患者符合选择标准纳入研究。男31例,女20例;年龄15~67岁,平均38.6岁。身体质量指数17.2~28.7 kg/m^(2),平均23.9 kg/m^(2)。左膝25例,右膝36例。受伤至入院时间0.1~14.3周,平均2.1周。术前均行伸膝0°(伸膝位)、屈膝90°(屈膝位)MRI检查,判断是否存在内侧半月板后缘不规则以及PHMM液体高信号[即内侧半月板后角(posterior horn of the medial meniscus,PHMM)与后囊之间充盈液体]征象。以关节镜探查结果为“金标准”,分别评估伸膝、屈膝位MRI对Ramp损伤两种特异征象的敏感度、特异度、准确度、阳性预测值及阴性预测值。结果经关节镜检查,21例(41.2%)确诊Ramp损伤,其中ThaunatⅠ型1例、Ⅱ型2例、Ⅲ型6例、Ⅳ型7例、Ⅴ型5例。伸膝位、屈膝位MRI示内侧半月板后缘不规则征象阳性率与关节镜下诊断Ramp损伤结果比较,差异均有统计学意义(P<0.05)。伸膝位MRI检查敏感度76.1%、特异度60.0%、准确度66.7%、阳性预测值57.1%、阴性预测值78.3%,屈膝位分别为85.7%、73.3%、78.4%、69.2%、88.0%。伸膝位、屈膝位MRI示PHMM液体高信号征象阳性率与关节镜下诊断Ramp损伤结果比较,差异亦有统计学意义(P<0.05);伸膝位MRI检查敏感度38.1%、特异度100%、准确度74.5%、阳性预测值100%、阴性预测值69.8%,屈膝位分别为85.7%、100%、94.1%、100%、90.9%。结论与传统伸膝0°MRI相比,基于屈膝90°MRI诊断内侧半月板Ramp损伤的敏感度、特异度和准确度均更高。展开更多
This paper analyzes the structural design of an urban interchange ramp bridge from four aspects,which are the superstructure,pier structure,foundation structure,and deck structure design to summarize the structural de...This paper analyzes the structural design of an urban interchange ramp bridge from four aspects,which are the superstructure,pier structure,foundation structure,and deck structure design to summarize the structural design ideas of this urban interchange ramp bridge,which can be used as a reference for future construction of the same bridge.展开更多
This article explores the fundamentals of small-radius curved ramp bridges.It covers the selection of box girder spans,support methods,and forms,along with design optimization techniques for this type of bridge struct...This article explores the fundamentals of small-radius curved ramp bridges.It covers the selection of box girder spans,support methods,and forms,along with design optimization techniques for this type of bridge structure.The purpose of this paper is to provide robust support for enhancing the design quality of these bridges and ensuring their efficacy in real-world applications.展开更多
Shock wave/boundary layer interaction in a 24°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical simulation.Three different jet spacings ...Shock wave/boundary layer interaction in a 24°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical simulation.Three different jet spacings which are termed as sparse,moderate and dense are considered,and the induced vortex system and shock structures are compared.A moderate jet spacing configuration is found to generate counter-rotating vortex pairs that transport high-momentum fluid towards the vicinity of wall and strengthen the boundary layer to resist separation,reducing the separation region.The dense jet spacing configuration creates a larger momentum deficit region,reducing the friction downstream of the corner.Analysis of pressure and pressure gradient reveals that dense jet spacing configuration reduces the intensity of separation shock.The impact of varying jet spacings on the turbulent kinetic energy transport mechanism is also investigated by decomposing the budget terms in the transport equation.Furthermore,the spectral characteristics of the separation region are studied using power spectral density and dynamic mode decomposition methods,revealing that moderate jet spacing configuration suppresses low-frequency fluctuations in the separation region.展开更多
With the increasing penetration of renewable energy in power system,renewable energy power ramp events(REPREs),dominated by wind power and photovoltaic power,pose significant threats to the secure and stable operation...With the increasing penetration of renewable energy in power system,renewable energy power ramp events(REPREs),dominated by wind power and photovoltaic power,pose significant threats to the secure and stable operation of power systems.This paper presents an early warning method for REPREs based on long short-term memory(LSTM)network and fuzzy logic.First,the warning levels of REPREs are defined by assessing the control costs of various power control measures.Then,the next 4-h power support capability of external grid is estimated by a tie line power predictionmodel,which is constructed based on the LSTMnetwork.Finally,considering the risk attitudes of dispatchers,fuzzy rules are employed to address the boundary value attribution of the early warning interval,improving the rationality of power ramp event early warning.Simulation results demonstrate that the proposed method can generate reasonable early warning levels for REPREs,guiding decision-making for control strategy.展开更多
Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck s...Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck stops are the only places for the trucks to stop legally and safely. In locations without sufficient parking areas, trucks often park on interstate ramps, which create safety risks for other interstate motorists. Historically, agencies have employed costly and time intensive manual counting methods, camera surveillance, and driver surveys to assess truck parking. Connected truck data, available in near real-time, offers an efficient alternative to practitioners to assess truck parking patterns and identify areas where there may be insufficient safe parking spaces. This paper presents a case study of interstate I-70 in east central Indiana and documents the observed spatiotemporal impacts of a rest area closure on truck parking on nearby interstate ramps. Results showed that there was a 28% increase in parking on ramps during the rest area closure. Analysis also found that ramps closest to the rest area were most impacted by the closure, seeing a rise in truck parking sessions as high as 2.7 times. Parking duration on the ramps during rest area closure also increased drastically. Although it was expected that this would result in increased parking by trucks on adjacent ramps, this before, during, after scenario provided an ideal scenario to evaluate the robustness of these techniques to assess changing parking characteristics of long-haul commercial trucks. The data analytics and visualization tools presented in this study are scalable nationwide and will aid stakeholders in informed data-driven decision making when allocating resources towards improving the nations commercial vehicle parking infrastructure.展开更多
文摘[目的]比较关节镜下缝合钩和Fast-fix缝合Ⅳ型半月板Ramp区损伤的临床疗效。[方法]回顾性分析2016年1月—2020年10月45例前交叉韧带(anterior cruciate ligament, ACL)损伤合并Ⅳ型半月板Ramp损伤患者的临床资料。所有患者均取自体腘绳肌腱行ACL重建,依据术前医患沟通结果,21例应用缝合钩缝合Ramp损伤,24例应用Fast-fix缝合。对比患者围手术期、随访及影像学结果。[结果]所有患者均顺利完成手术,术中未出现血管、神经损伤等并发症。缝合钩组手术时间[(91.2±10.6) min vs (62.5±8.4) min, P<0.001]、切口总长度[(5.9±0.5) cm vs (5.1±0.6) cm, P<0.001]均显著长于Fast-fix组,但前者住院费用显著少于后者[(3.4±0.3)万元vs (4.3±0.7)万元, P<0.001]。两组Ramp撕裂长度、缝合针数、下地行走时间、切口愈合、住院时间比较差异均无统计学意义(P>0.05)。所有患者均获36~72个月随访。两组完全负重活动时间的差异无统计学意义(P>0.05)。术后1年及末次随访时,两组膝间隙压痛、麦氏征,轴移征、膝关节屈伸ROM、IKDC评分及Lysholm评分较术前均显著改善(P<0.05)。同一时间点,两组上述指标的差异均无统计学意义(P>0.05)。影像方面,与术前相比,术后1年,两组半月板损伤分级及胫骨平台后侧骨髓水肿均显著改善(P<0.05),相应时间点,两组上述指标的差异均无统计学意义(P>0.05)。术后1年MRI显示缝合钩组愈合率为90.5%、Fast-fix组为87.5%,差异无统计学意义(P>0.05)。[结论]关节镜下缝合钩和Fast-fix缝合半月板Ramp区Ⅳ型损伤均可获得满意疗效。
基金Project(2023YFB2604304)supported by the National Key R&D Program of ChinaProjects(52122810,51978586,51778542,U23A20666,52472458)supported by the National Natural Science Foundation of China+1 种基金Project(K2022G034)supported by the Technology Research and Development Program of China National Railway Group Co.Ltd.Projects(2020JDJQ0033,2023NSFSC0884)supported by Sichuan Province Science and Technology Support Program,China。
文摘The influence of ramps on the transient rolling contact characteristics and damage mechanisms of switch rails remains unclear,presenting substantial challenges to the safety of railway operations.To this end,this paper constructs a transient rolling contact finite element model of the wheel-rail in switch under different ramps using ANSYS/LSDYNA method,and analyzes the tribology and damage characteristics when the wheel passes through the switch at a uniform speed.Our research findings reveal that the vibration induced in the switch rail during the wheel load transfer process leads to a step-like increase in the contact force.Moreover,the interaction between the wheel and the rail primarily involves slip contact,which may significantly contribute to the formation of corrugations on the switch rail.Additionally,the presence of large ramps exacerbates switch rail wear and rolling contact fatigue,resulting in a notable 13.2%increase in switch rail damage under 40‰ramp conditions compared to flat(0‰ramp)conditions.Furthermore,the large ramps can alter the direction of crack propagation,ultimately causing surface spalling of the rail.Therefore,large ramps intensify the dynamic interactions during the wheel load transfer process,further aggravating the crack and spalling damage to the switch rails.
文摘This paper represents a case study of traffic congestion within a section on Al Seeb Street highway due to the on-ramp merging of vehicles that causes a bottleneck in the mainline road. It studies the efficiency of installing ramp metering within a ramp within the selected study zone. This is done by simulating the collected data using Vissim software by drawing three one-hour-long scenarios;the first scenario reflects the data collected for 30 minutes duration and is used as a base scenario to draw the other two scenarios, which are reflected as factored-up scenarios to create a situation observed in the early morning in the study zone at 6:00-7:00 in which slowing down of speeds exist, and breakdown is raised in working days. The two factoring-up scenarios were as follows: one without ramp metering and the other without ramp metering. Each scenario was calibrated and run five times with random seeds, and then the average was considered. The simulation examines the ability of RM to smooth traffic in mainline and reduce queuing on on-ramp roads within the selected study zone by comparing the performance of the network for the scenarios and comparing them in terms of the overall delays, number of stops and the average speeds for the vehicles within the mainline. The results showed a good performance reflected by the scenario with ramp metering with a reduction of the overall delay, a decrease in stops number and an increase of the average speed were achieved. For the base scenario, a visualization (video extracted from Vissim software) was extracted, showing no need to install RM with an associated table showing a number of stops equal to zero with an average speed of 102.74 km/h and a total delay of 6045 seconds. For the second scenario with no RM, a visualization was extracted showing a slowing down of speeds for vehicles within the mainline while vehicles merging from the on-ramp and need to be controlled with a table showing a number of stops equal to 16 and an average speed equal to 58 km/h and a total delay of 916,874 seconds. For the third scenario with RM, a visualization was extracted showing good control of the second scenario with a table showing the number of stops equal to 6, an average speed equal to 61 km/h and a total delay equal to 484,466 seconds. Ten literatures in regard to this study have been reviewed. The data collected are quantitative, which are collected using an indirect manual counting method and then the data is used to feed the software for simulation.
文摘目的评价屈膝90°MRI对内侧半月板Ramp损伤的临床诊断价值。方法以2021年9月—2023年9月以膝关节疼痛为主诉收治的228例患者作为研究对象,其中51例患者符合选择标准纳入研究。男31例,女20例;年龄15~67岁,平均38.6岁。身体质量指数17.2~28.7 kg/m^(2),平均23.9 kg/m^(2)。左膝25例,右膝36例。受伤至入院时间0.1~14.3周,平均2.1周。术前均行伸膝0°(伸膝位)、屈膝90°(屈膝位)MRI检查,判断是否存在内侧半月板后缘不规则以及PHMM液体高信号[即内侧半月板后角(posterior horn of the medial meniscus,PHMM)与后囊之间充盈液体]征象。以关节镜探查结果为“金标准”,分别评估伸膝、屈膝位MRI对Ramp损伤两种特异征象的敏感度、特异度、准确度、阳性预测值及阴性预测值。结果经关节镜检查,21例(41.2%)确诊Ramp损伤,其中ThaunatⅠ型1例、Ⅱ型2例、Ⅲ型6例、Ⅳ型7例、Ⅴ型5例。伸膝位、屈膝位MRI示内侧半月板后缘不规则征象阳性率与关节镜下诊断Ramp损伤结果比较,差异均有统计学意义(P<0.05)。伸膝位MRI检查敏感度76.1%、特异度60.0%、准确度66.7%、阳性预测值57.1%、阴性预测值78.3%,屈膝位分别为85.7%、73.3%、78.4%、69.2%、88.0%。伸膝位、屈膝位MRI示PHMM液体高信号征象阳性率与关节镜下诊断Ramp损伤结果比较,差异亦有统计学意义(P<0.05);伸膝位MRI检查敏感度38.1%、特异度100%、准确度74.5%、阳性预测值100%、阴性预测值69.8%,屈膝位分别为85.7%、100%、94.1%、100%、90.9%。结论与传统伸膝0°MRI相比,基于屈膝90°MRI诊断内侧半月板Ramp损伤的敏感度、特异度和准确度均更高。
文摘This paper analyzes the structural design of an urban interchange ramp bridge from four aspects,which are the superstructure,pier structure,foundation structure,and deck structure design to summarize the structural design ideas of this urban interchange ramp bridge,which can be used as a reference for future construction of the same bridge.
文摘This article explores the fundamentals of small-radius curved ramp bridges.It covers the selection of box girder spans,support methods,and forms,along with design optimization techniques for this type of bridge structure.The purpose of this paper is to provide robust support for enhancing the design quality of these bridges and ensuring their efficacy in real-world applications.
基金Supported by the National Natural Science Foundation of China(Nos.11972064,92052104)the Key Laboratory of Computational Aerodynamics,AVIC Aerodynamics Research Institute,China(No.YL2022XFX0405)the Fundamental Research Funds for the Central Universities,China.
文摘Shock wave/boundary layer interaction in a 24°turning angle of the compression ramp at Mach number 2.9 controlled by steady microjet is investigated using direct numerical simulation.Three different jet spacings which are termed as sparse,moderate and dense are considered,and the induced vortex system and shock structures are compared.A moderate jet spacing configuration is found to generate counter-rotating vortex pairs that transport high-momentum fluid towards the vicinity of wall and strengthen the boundary layer to resist separation,reducing the separation region.The dense jet spacing configuration creates a larger momentum deficit region,reducing the friction downstream of the corner.Analysis of pressure and pressure gradient reveals that dense jet spacing configuration reduces the intensity of separation shock.The impact of varying jet spacings on the turbulent kinetic energy transport mechanism is also investigated by decomposing the budget terms in the transport equation.Furthermore,the spectral characteristics of the separation region are studied using power spectral density and dynamic mode decomposition methods,revealing that moderate jet spacing configuration suppresses low-frequency fluctuations in the separation region.
基金funded by State Grid Shandong Electric Power Company Technology Project(520626220110).
文摘With the increasing penetration of renewable energy in power system,renewable energy power ramp events(REPREs),dominated by wind power and photovoltaic power,pose significant threats to the secure and stable operation of power systems.This paper presents an early warning method for REPREs based on long short-term memory(LSTM)network and fuzzy logic.First,the warning levels of REPREs are defined by assessing the control costs of various power control measures.Then,the next 4-h power support capability of external grid is estimated by a tie line power predictionmodel,which is constructed based on the LSTMnetwork.Finally,considering the risk attitudes of dispatchers,fuzzy rules are employed to address the boundary value attribution of the early warning interval,improving the rationality of power ramp event early warning.Simulation results demonstrate that the proposed method can generate reasonable early warning levels for REPREs,guiding decision-making for control strategy.
文摘Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck stops are the only places for the trucks to stop legally and safely. In locations without sufficient parking areas, trucks often park on interstate ramps, which create safety risks for other interstate motorists. Historically, agencies have employed costly and time intensive manual counting methods, camera surveillance, and driver surveys to assess truck parking. Connected truck data, available in near real-time, offers an efficient alternative to practitioners to assess truck parking patterns and identify areas where there may be insufficient safe parking spaces. This paper presents a case study of interstate I-70 in east central Indiana and documents the observed spatiotemporal impacts of a rest area closure on truck parking on nearby interstate ramps. Results showed that there was a 28% increase in parking on ramps during the rest area closure. Analysis also found that ramps closest to the rest area were most impacted by the closure, seeing a rise in truck parking sessions as high as 2.7 times. Parking duration on the ramps during rest area closure also increased drastically. Although it was expected that this would result in increased parking by trucks on adjacent ramps, this before, during, after scenario provided an ideal scenario to evaluate the robustness of these techniques to assess changing parking characteristics of long-haul commercial trucks. The data analytics and visualization tools presented in this study are scalable nationwide and will aid stakeholders in informed data-driven decision making when allocating resources towards improving the nations commercial vehicle parking infrastructure.
