Affected by the limited interchange spacing,the operational risk of vehicles in expressway small-spacing interchanges(SSIs)is more complex compared to other interchanges.In this study,unmanned aerial vehicle(UAV)measu...Affected by the limited interchange spacing,the operational risk of vehicles in expressway small-spacing interchanges(SSIs)is more complex compared to other interchanges.In this study,unmanned aerial vehicle(UAV)measurements were integrated with joint simulation data to explore the risk characteristics of SSIs with the help of traffic conflict theory.Seven traffic flow parameters,including mainline traffic volume,were selected to evaluate their impact on traffic conflicts.The distribution of four traffic conflict indicators,such as time to collision(TTC),was analyzed,and their severity was categorized using cumulative frequency analysis and minibatch K-means clustering.By varying the spacing,the study scrutinized trends in traffic conflicts,emphasizing the influence of various traffic flow parameters,distinctions in conflict indicators,and the ratio of severe conflicts to total conflicts.Additionally,an analysis of the spatial distribution of severe conflicts was conducted.The results suggested that traffic conflicts in SSIs are influenced by multiple factors,with mainline and entry traffic volumes being the most significant.Heavy vehicle proportions and entry ramp speeds had notable effects under certain spacing conditions.Considerable variations were observed in conflict indicators across different spacings,with the maximum conflict speed being the most affected by spacing,while TTC was the least.As spacing increased,the proportion of severe conflicts decreased,with severe TTC dropping from 18%to 10%.High-density conflict zones were identified near merging points in the second and third lanes.With larger spacing,the conflict zone range narrowed while the density of conflict points intensified.展开更多
Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a ...Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a long service life.The breaking mechanism significantly affects the current interruption capability of DCCBs.The operation of the repulsion mechanism,along with the morphology of the arc and its transformation within the interrupter chamber,collectively influence the breaking performance of the FMSs.This paper presents a comprehensive analysis of the FMSs,which serves as the pivotal component of controlled resonance combination circuit breakers(CRCBs).This study establishes a multi physics coupling simulation analysis method based on the equivalent circuit of repulsion mechanism discharge,combined with electromagnetic and solid mechanics fields.By constructing a full cycle magnetohydrodynamic particle arc(MHP)model and using a combined simulation of Finite Element joint model(FEJM),the evolution law of arc characteristics during the superimposed current interruption process was systematically explored.The focus was on analysing the physical process of the zero zone of the superimposed arc,the multi physics field coupling relationship of the arc,and the interaction mechanism with external characteristic parameters.Further combining with optimisation design methods,the effectiveness of the model was verified through experiments,FEJM provides comprehensive technical support for effectively reflecting the stress issues of core components during the breaking process of FMS and can provide accurate theoretical references for the optimisation design of mechanical motion components in FMS.It also accurately represents the arc extinguishing process during the breaking of FMS and provides a convenient method for the selection and design of circuit parameters for the entire circuit breaker.展开更多
In the field of optoelectronics,certain types of data may be difficult to accurately annotate,such as high-resolution optoelectronic imaging or imaging in certain special spectral ranges.Weakly supervised learning can...In the field of optoelectronics,certain types of data may be difficult to accurately annotate,such as high-resolution optoelectronic imaging or imaging in certain special spectral ranges.Weakly supervised learning can provide a more reliable approach in these situations.Current popular approaches mainly adopt the classification-based class activation maps(CAM)as initial pseudo labels to solve the task.展开更多
A biomimetic hip joint simulator that can be used to evaluate the outcome of the cemented total hip replacement has been designed, manufactured and evaluated. The simulator produces motion in the extension/flexion pla...A biomimetic hip joint simulator that can be used to evaluate the outcome of the cemented total hip replacement has been designed, manufactured and evaluated. The simulator produces motion in the extension/flexion plane, with a socket to rotate internal/externally. At the same time a dynamic loading cycle is applied. A validation test was performed on a cemented femoral stem within a novel composite femur. The hone quality has a strong effect on the stem migration and on the integrity of the interfaces. The migration of the stem is a combination of 3-D translation and rotation of the stem. Under the same loading conditions, weak bone allows more stem migration than strong bone. There is a great decrease in the strength of the stem-cement interface after the dynamic test, and the weak bone composite exhibited a greater reduction in interfacial strength than the strong bone composite. The decrease of the interfacial strength indicates that the primary bonding between the stem and the cement mantle had deteriorated and the integrity of stem-cement interface was damaged. The study demonstrates the value of using a hip joint simulator to investigate stem migration and interface integrity within the cemented hip replacement, suggesting that method can be used for in vitro evaluation of the biomaterials used in the cemented hip replacements.展开更多
基金supported in part by the National Natural Science Foundation of China(No.52172340).
文摘Affected by the limited interchange spacing,the operational risk of vehicles in expressway small-spacing interchanges(SSIs)is more complex compared to other interchanges.In this study,unmanned aerial vehicle(UAV)measurements were integrated with joint simulation data to explore the risk characteristics of SSIs with the help of traffic conflict theory.Seven traffic flow parameters,including mainline traffic volume,were selected to evaluate their impact on traffic conflicts.The distribution of four traffic conflict indicators,such as time to collision(TTC),was analyzed,and their severity was categorized using cumulative frequency analysis and minibatch K-means clustering.By varying the spacing,the study scrutinized trends in traffic conflicts,emphasizing the influence of various traffic flow parameters,distinctions in conflict indicators,and the ratio of severe conflicts to total conflicts.Additionally,an analysis of the spatial distribution of severe conflicts was conducted.The results suggested that traffic conflicts in SSIs are influenced by multiple factors,with mainline and entry traffic volumes being the most significant.Heavy vehicle proportions and entry ramp speeds had notable effects under certain spacing conditions.Considerable variations were observed in conflict indicators across different spacings,with the maximum conflict speed being the most affected by spacing,while TTC was the least.As spacing increased,the proportion of severe conflicts decreased,with severe TTC dropping from 18%to 10%.High-density conflict zones were identified near merging points in the second and third lanes.With larger spacing,the conflict zone range narrowed while the density of conflict points intensified.
基金State Grid Corporation Headquarters Science and Technology Project,Grant/Award Number:5500-20220110A-1-1-ZN。
文摘Fast mechanical switches(FMSs)are critical components of DC circuit breakers(DCCBs),which require the switch action time to break to a sufficient distance within 3 ms in the DC line breaking scenario,while ensuring a long service life.The breaking mechanism significantly affects the current interruption capability of DCCBs.The operation of the repulsion mechanism,along with the morphology of the arc and its transformation within the interrupter chamber,collectively influence the breaking performance of the FMSs.This paper presents a comprehensive analysis of the FMSs,which serves as the pivotal component of controlled resonance combination circuit breakers(CRCBs).This study establishes a multi physics coupling simulation analysis method based on the equivalent circuit of repulsion mechanism discharge,combined with electromagnetic and solid mechanics fields.By constructing a full cycle magnetohydrodynamic particle arc(MHP)model and using a combined simulation of Finite Element joint model(FEJM),the evolution law of arc characteristics during the superimposed current interruption process was systematically explored.The focus was on analysing the physical process of the zero zone of the superimposed arc,the multi physics field coupling relationship of the arc,and the interaction mechanism with external characteristic parameters.Further combining with optimisation design methods,the effectiveness of the model was verified through experiments,FEJM provides comprehensive technical support for effectively reflecting the stress issues of core components during the breaking process of FMS and can provide accurate theoretical references for the optimisation design of mechanical motion components in FMS.It also accurately represents the arc extinguishing process during the breaking of FMS and provides a convenient method for the selection and design of circuit parameters for the entire circuit breaker.
文摘In the field of optoelectronics,certain types of data may be difficult to accurately annotate,such as high-resolution optoelectronic imaging or imaging in certain special spectral ranges.Weakly supervised learning can provide a more reliable approach in these situations.Current popular approaches mainly adopt the classification-based class activation maps(CAM)as initial pseudo labels to solve the task.
文摘A biomimetic hip joint simulator that can be used to evaluate the outcome of the cemented total hip replacement has been designed, manufactured and evaluated. The simulator produces motion in the extension/flexion plane, with a socket to rotate internal/externally. At the same time a dynamic loading cycle is applied. A validation test was performed on a cemented femoral stem within a novel composite femur. The hone quality has a strong effect on the stem migration and on the integrity of the interfaces. The migration of the stem is a combination of 3-D translation and rotation of the stem. Under the same loading conditions, weak bone allows more stem migration than strong bone. There is a great decrease in the strength of the stem-cement interface after the dynamic test, and the weak bone composite exhibited a greater reduction in interfacial strength than the strong bone composite. The decrease of the interfacial strength indicates that the primary bonding between the stem and the cement mantle had deteriorated and the integrity of stem-cement interface was damaged. The study demonstrates the value of using a hip joint simulator to investigate stem migration and interface integrity within the cemented hip replacement, suggesting that method can be used for in vitro evaluation of the biomaterials used in the cemented hip replacements.
