Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This pap...Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.展开更多
The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relat...The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point(Q-L relation)is mostly nonlinear.Therefore,the linear Q-L relation in the traditional fault location method always leads to large errors.To solve this problem,a large number of load-related current data that can be used to describe the Q-L relation are obtained through the load test of the electric multiple unit(EMU).Thus,an improved fault location method based on the back propagation(BP)neural network is proposed in this paper.On this basis,a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method,respectively,which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network.Finally,combined with a shortcircuit test,the accuracy of the improved method is verified.展开更多
The features of three modes of AT-fed traction power networks (TPNs) have been briefly described in the existing literature, which is not adequate yet. In this paper, these three modes of TPNs are compared mainly on T...The features of three modes of AT-fed traction power networks (TPNs) have been briefly described in the existing literature, which is not adequate yet. In this paper, these three modes of TPNs are compared mainly on TPN capacity, transformer capacity, rail potential and voltage level, etc., and conclusions are drawn.展开更多
Mechanobiology has been a highly recognized field in studying the importance of physical forces in physiologies at the molecular,cellular,tissue,organ and body-levels.Beside the intensive work focusing on the fine loc...Mechanobiology has been a highly recognized field in studying the importance of physical forces in physiologies at the molecular,cellular,tissue,organ and body-levels.Beside the intensive work focusing on the fine local biomechanical forces,the long-range force which can propagate through a relatively distant scale(in hundreds of micrometers and beyond)has been an intriguing topic with increasing attentions in recent years.The collective functions at cell population level often rely on cell-cell communications with or without direct contacts.Recent progresses including our own work indicate that the long-range biomechanical force propagating across scales far beyond single cell size may reserve the capability to trigger coordinative biological responses within cell population.Whether and how cells communicate mechanically in a distant manner remains largely to be explored.In respiratory system,the mechanical property of airway smooth muscle(ASM)is associated with asthma attack with prolonged contraction during airway hyper-responsiveness.In this work,we found that ASM cells rapidly self-assembled into a well-constructed network on 3D matrigel containing type I collagen(COL I),which required the collective functions and coordination of thousands of cells completed within 12-16 hours.Cells were assembled with aligned actin stress fibers and elongated nuclei.The assembling process relied on the long-range mechanical forces across the matrix to direct cell-cell distant interactions.We further found that single ASM cells could rapidly initiate multiple buds precisely pointing to neighboring cells in distance,which relied on cell traction force and force strain on the matrix.Beads tracking assay demonstrated the long-range transmission of cellular traction force to distant locations,and modeling of maximum strain distribution on matrix by finite element method predicted the consistency with cell directional protrusions and movements in experiments.Cells could sense each other in distance to move directionally on both non-fibrous matrigel and in much more efficient way when containing COL I.Cells recruited COL I from the hydrogel to build nearly identical COL I fibrous network to mechanically stabilize the cell network.Our results revealed that ASM cells can sense the traction strain transmitted through matrix to initiate distant communications and rapidly coordinate the network assembly at the population level through active cell-matrix interactions.As an interesting phenomenon,cells sound able to’make phone call’via the role of long-range mechanical force.In summary,this work demonstrated that long-range biomechanical force facilitates the collective functions of ASM cell population for network assembly.The cells reacted to traction strain on the matrix for distant communications,which resulted in directional budding and movement.Fibrous COL I had important roles in facilitating the efficiency of force transmission to induce the assembly and stabilizing the cell network.This work has helped advance the understanding of the feature andfunction of long-range biomechanical force at the cell population level.The observed high mechano-sensitivity of ASM cells might suggest a re-enforced feedback of enhanced contraction by excessive ASM under asthmatic condition.展开更多
基金funded by Youth Science Foundation Fund Project of National Natural Science Foundation of China(51607148)Science and Technology R&D Program of China State Railway Group Co.,Ltd.(SY2020G001)Project of Sichuan Science and Technology Program(2021YJ0028)。
文摘Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.
基金supported by the National Key Research and Development Program of China(No.2021YFB2601500)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0405)。
文摘The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point(Q-L relation)is mostly nonlinear.Therefore,the linear Q-L relation in the traditional fault location method always leads to large errors.To solve this problem,a large number of load-related current data that can be used to describe the Q-L relation are obtained through the load test of the electric multiple unit(EMU).Thus,an improved fault location method based on the back propagation(BP)neural network is proposed in this paper.On this basis,a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method,respectively,which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network.Finally,combined with a shortcircuit test,the accuracy of the improved method is verified.
文摘The features of three modes of AT-fed traction power networks (TPNs) have been briefly described in the existing literature, which is not adequate yet. In this paper, these three modes of TPNs are compared mainly on TPN capacity, transformer capacity, rail potential and voltage level, etc., and conclusions are drawn.
基金supported financially by Natural Science Foundation of China ( 11532003,11872129, 31670950)Natural Science Foundation of Jiangsu Province ( BK20181416)CZSTB Grant ( CZ20180017) from Changzhou City,Jiangsu Province
文摘Mechanobiology has been a highly recognized field in studying the importance of physical forces in physiologies at the molecular,cellular,tissue,organ and body-levels.Beside the intensive work focusing on the fine local biomechanical forces,the long-range force which can propagate through a relatively distant scale(in hundreds of micrometers and beyond)has been an intriguing topic with increasing attentions in recent years.The collective functions at cell population level often rely on cell-cell communications with or without direct contacts.Recent progresses including our own work indicate that the long-range biomechanical force propagating across scales far beyond single cell size may reserve the capability to trigger coordinative biological responses within cell population.Whether and how cells communicate mechanically in a distant manner remains largely to be explored.In respiratory system,the mechanical property of airway smooth muscle(ASM)is associated with asthma attack with prolonged contraction during airway hyper-responsiveness.In this work,we found that ASM cells rapidly self-assembled into a well-constructed network on 3D matrigel containing type I collagen(COL I),which required the collective functions and coordination of thousands of cells completed within 12-16 hours.Cells were assembled with aligned actin stress fibers and elongated nuclei.The assembling process relied on the long-range mechanical forces across the matrix to direct cell-cell distant interactions.We further found that single ASM cells could rapidly initiate multiple buds precisely pointing to neighboring cells in distance,which relied on cell traction force and force strain on the matrix.Beads tracking assay demonstrated the long-range transmission of cellular traction force to distant locations,and modeling of maximum strain distribution on matrix by finite element method predicted the consistency with cell directional protrusions and movements in experiments.Cells could sense each other in distance to move directionally on both non-fibrous matrigel and in much more efficient way when containing COL I.Cells recruited COL I from the hydrogel to build nearly identical COL I fibrous network to mechanically stabilize the cell network.Our results revealed that ASM cells can sense the traction strain transmitted through matrix to initiate distant communications and rapidly coordinate the network assembly at the population level through active cell-matrix interactions.As an interesting phenomenon,cells sound able to’make phone call’via the role of long-range mechanical force.In summary,this work demonstrated that long-range biomechanical force facilitates the collective functions of ASM cell population for network assembly.The cells reacted to traction strain on the matrix for distant communications,which resulted in directional budding and movement.Fibrous COL I had important roles in facilitating the efficiency of force transmission to induce the assembly and stabilizing the cell network.This work has helped advance the understanding of the feature andfunction of long-range biomechanical force at the cell population level.The observed high mechano-sensitivity of ASM cells might suggest a re-enforced feedback of enhanced contraction by excessive ASM under asthmatic condition.
