Purpose-Under the high-speed operating conditions,the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition.In order to meet different an...Purpose-Under the high-speed operating conditions,the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition.In order to meet different analysis requirements and selecting appropriate models to analyzing the wheel rail interaction,it is crucial to understand the influence of wheelset flexibility on the wheel-rail dynamics under different speeds and track excitations condition.Design/methodology/approach-The wheel rail contact points solving method and vehicle dynamics equations considering wheelset flexibility in the trajectory body coordinate system were investigated in this paper.As for the wheel-rail contact forces,which is a particular force element in vehicle multibody system,a method for calculating the Jacobian matrix of the wheel-rail contact force is proposed to better couple the wheel-rail contact force calculation with the vehicle dynamics response calculation.Based on the flexible wheelset modeling approach in this paper,two vehicle dynamic models considering the wheelset as both elastic and rigid bodies are established,two kinds of track excitations,namely normal measured track irregularities and short-wave irregularities are used,wheel-rail geometric contact characteristic and wheel-rail contact forces in both time and frequency domains are compared with the two models in order to study the influence of flexible wheelset rotation effect on wheel rail contact force.Findings-Under normal track irregularity excitations,the amplitudes of vertical,longitudinal and lateral forces computed by the flexible wheelset model are smaller than those of the rigid wheelset model,and the virtual penetration and equivalent contact patch are also slightly smaller.For the flexible wheelset model,the wheel rail longitudinal and lateral creepages will also decrease.The higher the vehicle speed,the larger the differences in wheel-rail forces computed by the flexible and rigid wheelset model.Under track short-wave irregularity excitations,the vertical force amplitude computed by the flexible wheelset is also smaller than that of the rigid wheelset.However,unlike the excitation case of measured track irregularity,under short-wave excitations,for the speed within the range of 200 to 350 km/h,the difference in the amplitude of the vertical force between the flexible and rigid wheelset models gradually decreases as the speed increase.This is partly due to the contribution of wheelset's elastic vibration under short-wave excitations.For low-frequency wheel-rail force analysis problems at speeds of 350 km/h and above,as well as high-frequency wheel-rail interaction analysis problems under various speed conditions,the flexible wheelset model will give results agrees better with the reality.Originality/value-This study provides reference for the modeling method of the flexible wheelset and the coupling method of wheel-rail contact force to the vehicle multibody dynamics system.Furthermore,by comparative research,the influence of wheelset flexibility and rotation on wheel-rail dynamic behavior are obtained,which is useful to the application scope of rigid and flexible wheelset models.展开更多
BACKGROUND： It is hard to cure the open traumatic brain injury （TBI）, especially for the brain functional recovery after brain injury. In this regard, traditional Chinese medicine （TCM） has a wide prospect. OBJEC...BACKGROUND： It is hard to cure the open traumatic brain injury （TBI）, especially for the brain functional recovery after brain injury. In this regard, traditional Chinese medicine （TCM） has a wide prospect. OBJECTIVE： To observe the effect of Huayu capsule on limb-catching capability of rat models of open TBI, and investigate its possible mechanism. DESIGN： Randomized and controlled study. SETTING： Grade 3 Pharmacological Laboratory of TCM, State Administration of TCM, Chengdu University of TCM. MATERIALS： This study was performed from October 2005 to January 2006. Fifty Sprague-Dawley rats of either gender, aged 3 months old, weighing from 190 to 220 g, were involved in this study. Huayu capsule was made and supplied by the Department of TCM Processing of Chengdu University of TCM, Lot No. 050121; Xuefuzhuyu oral liquid was manufactured by Jilin Aodong Yanbian Pharmaceutical Industry Co.,Ltd., Lot No. 050406. METHODS： Open right parietal lobe TBI rat models were made as described in references. The involved rat models were randomized into 5 groups according to gender and body mass： model group, high-, middle-, low-dose Huayu capsule groups and Xuefuzhuyu oral liquid group, with 10 rats in each. Rats in the model group were administrated with distilled water of 5 mL/kg; Rats in the high-, middle- and low-dose Huayu capsule groups were administrated with 1.030, 0.515, 0.258 g/kg raw herbs; Rats in the Xuefuzhuyu oral liquid group were administrated with Xuefuzhuyu oral liquid of 5 mL/kg, intragastrically once a day for 7 days successively for all after recovering consciousness from anesthetization. ① One hour after administration on the 6^th day, rats in each group were placed on a 100 cm fine straight iron wire paralleling to the ground and 20 cm above the operational table. The time of the rats keeping on the wire was counted and it indicated the nerve-muscle catching capability. The longer the remained time, the better the nerve-muscle catching capability.② Twenty-four hours after the administration on the 7^th day, the samples of the whole brain were carefully taken out and stained by toluidine blue for observing the morphology of cells in the injured brain tissue. ③ The nerve cells in 4 visual fields from 4 directions （upper, lower, left, right） of injured area of brain tissue were counted. The amount was the total number of the four visual fields. The nerve cells in the injured brain tissue were measured by the same way. ④ On the basis of nerve cell counting, the content of Nissl＇s body in the corresponding nerve cells was measured. MAIN OUTCOME MEASURES： ①Nerve-muscle catching capability. ②Histopathomorphological examination of the injured areas in brain. ③Measurement of nerve cells and macrophages in the injured areas of brain. ④Measurement of content of Nissl＇s body in the injured areas of brain. RESULTS： All the 50 rats were involved in the final analysis. ①The catching time of rats in the high- and middle-dose Huayu capsule groups as well as Xuefuzhuyu oral liquid group was extended to （ 23.6 ± 10.12 ）, （ 18.6 ± 8.17 ） and （22.6 ± 9.43） s, respectively, which was significantly higher than that in the model group [ （12.1 ± 4.15） s, P 〈 0.05 - 0.01 ]. ② The injured areas of brain tissue of rats in the Huayu capsule-treated groups and Xuefuzhuyu oral liquid group were decreased to different extents. The nerve cells adjacent to brain injured area were increased. ③ The number of macrophages around the brain injured area of rats in the high- and middle-dose Huayu capsule groups as well as Xuefuzhuyu oral liquid group was 63.9 ± 7.99, 59.7 ± 7.41 and 62.9 ± 7.37, respectively, which was significantly larger than that in the model group （49.2 ± 8.00, P 〈 0.01 ） . The number of nerve cells adjacent to brain injured area of rats in the high-, middle-, and low-dose Huayu capsule groups as well as Xuefuzhuyu oral liquid group was 86.2 ± 25.93, 93.5 ± 31.79, 92.1 ± 14.54 and 125.2 ±34.25, respectively, which was significantly larger than that in the model group （62.5 ± 16.98, P 〈 0.05 -0.01 ） .④ The total area, the total and integral absorbance, the average gray degree of Nissl＇s body in the cytoplasm of nerve cells of rats in the Huayu capsule-treated groups and Xuefuzhuyu oral liquid group were all significantly increased （P 〈 0.05 - 0.01）. CONCLUSION： Huayu capsule at different doses can promote the limb-catching capability of rat models of open TBI to different extent. This promoting effect may be related to increasing macrophages in the injured area, lessening the apoptosis of nerve cells and increasing the content of Nissl＇s body in the nerve cells.展开更多
Despite the high theoretical specific capacity,the main challenges of rechargeable lithium-sulfur(Li-S)batteries,including the unceasing shuttle of soluble lithium polysulfides(LiPSs)and severe Li corrosion,seriously ...Despite the high theoretical specific capacity,the main challenges of rechargeable lithium-sulfur(Li-S)batteries,including the unceasing shuttle of soluble lithium polysulfides(LiPSs)and severe Li corrosion,seriously hinder their commercial and practical applications.Herein,a bifunctional polyvinyl alcohol/poly(lithium acrylate)(C-PVA/PAA-Li)composite nanofiber separator is developed to address the main challenges in Li-S batteries by simultaneously allowing rapid lithium ion transport and ionic shielding of polysulfides.The C-PVA/PAA-Li composite nanofiber membrane is prepared via the facile electrospinning strategy,followed by thermal crosslinking and in-situ lithiation processes.Differing from the conventional Celgard-based coating methods accompanied by impaired lithium ion transport efficiency,the C-PVA/PAA-Li composite nanofiber membrane possesses well-developed porous structures and high ionic conductivity,thus synergistically reducing the charge transfer resistance and inhibiting the growth of lithium dendrites.The resulting Li-S batteries exhibit an ultra-low fading rate of 0.08%per cycle after 400 cycles at 0.2 C,and a capacity of 633 mAhg−1 at a high current density of 3 C.This study presents an inspiring and promising strategy to fabricate emerging dual-functional separators,which paves the pathway for the practical implementation of ultra-stable and reliable Li-S battery systems.展开更多
Uncontrolled lithium dendrite growth hinders the practical application of lithium metal batteries(LMBs).Herein,we report a novel Li^(+) flux distributor achieved by placing an electroactive polyvinylidene fluoride/pol...Uncontrolled lithium dendrite growth hinders the practical application of lithium metal batteries(LMBs).Herein,we report a novel Li^(+) flux distributor achieved by placing an electroactive polyvinylidene fluoride/polymethyl methacrylate(PVDF/PMMA)composite nanofiber interlayer on a current collector,inducing uniform lithium deposition to mitigate the dendrite problem.Specifically,the released PMMA reacts with Liþto form abundant C–O–Li bonds and generate in situ a stable lithiophilic PMMA-Li solid electrolyte interphase layer.Theoretical calculations reveal that polar C–F groups in the PVDF framework and lithiophilic PMMA-Li provide homo-dispersed Li^(+) migration pathways with low energy barriers.Consequently,uniform Li nucleation is achieved at the molecular level,resulting in ultrahigh cycling stability with dendrite-free Li deposition at 5 mA cm^(-2) and 5 mAh cm^(-2)for over 500 h.The PVDF/PMMA||Li||LiFePO_(4)(LFP)full cell presents an increased rate capacity of 110 mAh g^(-1) at 10 C.In addition,a soft-package battery demonstrates a high energy density of 289 Wh kg^(-1).This work provides a facile design for stable lithium metal anodes to promote the practical use of LMBs and other alkali metal batteries.展开更多
基金China National Railway Group Science and Technology Program(N2022J009)China Academy of Railway Sciences Group Co.,Ltd.Program(2021YJ036).
文摘Purpose-Under the high-speed operating conditions,the effects of wheelset elastic deformation on the wheel rail dynamic forces will become more notable compared to the low-speed condition.In order to meet different analysis requirements and selecting appropriate models to analyzing the wheel rail interaction,it is crucial to understand the influence of wheelset flexibility on the wheel-rail dynamics under different speeds and track excitations condition.Design/methodology/approach-The wheel rail contact points solving method and vehicle dynamics equations considering wheelset flexibility in the trajectory body coordinate system were investigated in this paper.As for the wheel-rail contact forces,which is a particular force element in vehicle multibody system,a method for calculating the Jacobian matrix of the wheel-rail contact force is proposed to better couple the wheel-rail contact force calculation with the vehicle dynamics response calculation.Based on the flexible wheelset modeling approach in this paper,two vehicle dynamic models considering the wheelset as both elastic and rigid bodies are established,two kinds of track excitations,namely normal measured track irregularities and short-wave irregularities are used,wheel-rail geometric contact characteristic and wheel-rail contact forces in both time and frequency domains are compared with the two models in order to study the influence of flexible wheelset rotation effect on wheel rail contact force.Findings-Under normal track irregularity excitations,the amplitudes of vertical,longitudinal and lateral forces computed by the flexible wheelset model are smaller than those of the rigid wheelset model,and the virtual penetration and equivalent contact patch are also slightly smaller.For the flexible wheelset model,the wheel rail longitudinal and lateral creepages will also decrease.The higher the vehicle speed,the larger the differences in wheel-rail forces computed by the flexible and rigid wheelset model.Under track short-wave irregularity excitations,the vertical force amplitude computed by the flexible wheelset is also smaller than that of the rigid wheelset.However,unlike the excitation case of measured track irregularity,under short-wave excitations,for the speed within the range of 200 to 350 km/h,the difference in the amplitude of the vertical force between the flexible and rigid wheelset models gradually decreases as the speed increase.This is partly due to the contribution of wheelset's elastic vibration under short-wave excitations.For low-frequency wheel-rail force analysis problems at speeds of 350 km/h and above,as well as high-frequency wheel-rail interaction analysis problems under various speed conditions,the flexible wheelset model will give results agrees better with the reality.Originality/value-This study provides reference for the modeling method of the flexible wheelset and the coupling method of wheel-rail contact force to the vehicle multibody dynamics system.Furthermore,by comparative research,the influence of wheelset flexibility and rotation on wheel-rail dynamic behavior are obtained,which is useful to the application scope of rigid and flexible wheelset models.
文摘BACKGROUND： It is hard to cure the open traumatic brain injury （TBI）, especially for the brain functional recovery after brain injury. In this regard, traditional Chinese medicine （TCM） has a wide prospect. OBJECTIVE： To observe the effect of Huayu capsule on limb-catching capability of rat models of open TBI, and investigate its possible mechanism. DESIGN： Randomized and controlled study. SETTING： Grade 3 Pharmacological Laboratory of TCM, State Administration of TCM, Chengdu University of TCM. MATERIALS： This study was performed from October 2005 to January 2006. Fifty Sprague-Dawley rats of either gender, aged 3 months old, weighing from 190 to 220 g, were involved in this study. Huayu capsule was made and supplied by the Department of TCM Processing of Chengdu University of TCM, Lot No. 050121; Xuefuzhuyu oral liquid was manufactured by Jilin Aodong Yanbian Pharmaceutical Industry Co.,Ltd., Lot No. 050406. METHODS： Open right parietal lobe TBI rat models were made as described in references. The involved rat models were randomized into 5 groups according to gender and body mass： model group, high-, middle-, low-dose Huayu capsule groups and Xuefuzhuyu oral liquid group, with 10 rats in each. Rats in the model group were administrated with distilled water of 5 mL/kg; Rats in the high-, middle- and low-dose Huayu capsule groups were administrated with 1.030, 0.515, 0.258 g/kg raw herbs; Rats in the Xuefuzhuyu oral liquid group were administrated with Xuefuzhuyu oral liquid of 5 mL/kg, intragastrically once a day for 7 days successively for all after recovering consciousness from anesthetization. ① One hour after administration on the 6^th day, rats in each group were placed on a 100 cm fine straight iron wire paralleling to the ground and 20 cm above the operational table. The time of the rats keeping on the wire was counted and it indicated the nerve-muscle catching capability. The longer the remained time, the better the nerve-muscle catching capability.② Twenty-four hours after the administration on the 7^th day, the samples of the whole brain were carefully taken out and stained by toluidine blue for observing the morphology of cells in the injured brain tissue. ③ The nerve cells in 4 visual fields from 4 directions （upper, lower, left, right） of injured area of brain tissue were counted. The amount was the total number of the four visual fields. The nerve cells in the injured brain tissue were measured by the same way. ④ On the basis of nerve cell counting, the content of Nissl＇s body in the corresponding nerve cells was measured. MAIN OUTCOME MEASURES： ①Nerve-muscle catching capability. ②Histopathomorphological examination of the injured areas in brain. ③Measurement of nerve cells and macrophages in the injured areas of brain. ④Measurement of content of Nissl＇s body in the injured areas of brain. RESULTS： All the 50 rats were involved in the final analysis. ①The catching time of rats in the high- and middle-dose Huayu capsule groups as well as Xuefuzhuyu oral liquid group was extended to （ 23.6 ± 10.12 ）, （ 18.6 ± 8.17 ） and （22.6 ± 9.43） s, respectively, which was significantly higher than that in the model group [ （12.1 ± 4.15） s, P 〈 0.05 - 0.01 ]. ② The injured areas of brain tissue of rats in the Huayu capsule-treated groups and Xuefuzhuyu oral liquid group were decreased to different extents. The nerve cells adjacent to brain injured area were increased. ③ The number of macrophages around the brain injured area of rats in the high- and middle-dose Huayu capsule groups as well as Xuefuzhuyu oral liquid group was 63.9 ± 7.99, 59.7 ± 7.41 and 62.9 ± 7.37, respectively, which was significantly larger than that in the model group （49.2 ± 8.00, P 〈 0.01 ） . The number of nerve cells adjacent to brain injured area of rats in the high-, middle-, and low-dose Huayu capsule groups as well as Xuefuzhuyu oral liquid group was 86.2 ± 25.93, 93.5 ± 31.79, 92.1 ± 14.54 and 125.2 ±34.25, respectively, which was significantly larger than that in the model group （62.5 ± 16.98, P 〈 0.05 -0.01 ） .④ The total area, the total and integral absorbance, the average gray degree of Nissl＇s body in the cytoplasm of nerve cells of rats in the Huayu capsule-treated groups and Xuefuzhuyu oral liquid group were all significantly increased （P 〈 0.05 - 0.01）. CONCLUSION： Huayu capsule at different doses can promote the limb-catching capability of rat models of open TBI to different extent. This promoting effect may be related to increasing macrophages in the injured area, lessening the apoptosis of nerve cells and increasing the content of Nissl＇s body in the nerve cells.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(No.21604010)the Natural Science Foundation of Shanghai(No.18ZR1401600)+1 种基金“Chenguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.16CG39)Shanghai Scientific and Technological Innovation Project(No.18JC1410600).
文摘Despite the high theoretical specific capacity,the main challenges of rechargeable lithium-sulfur(Li-S)batteries,including the unceasing shuttle of soluble lithium polysulfides(LiPSs)and severe Li corrosion,seriously hinder their commercial and practical applications.Herein,a bifunctional polyvinyl alcohol/poly(lithium acrylate)(C-PVA/PAA-Li)composite nanofiber separator is developed to address the main challenges in Li-S batteries by simultaneously allowing rapid lithium ion transport and ionic shielding of polysulfides.The C-PVA/PAA-Li composite nanofiber membrane is prepared via the facile electrospinning strategy,followed by thermal crosslinking and in-situ lithiation processes.Differing from the conventional Celgard-based coating methods accompanied by impaired lithium ion transport efficiency,the C-PVA/PAA-Li composite nanofiber membrane possesses well-developed porous structures and high ionic conductivity,thus synergistically reducing the charge transfer resistance and inhibiting the growth of lithium dendrites.The resulting Li-S batteries exhibit an ultra-low fading rate of 0.08%per cycle after 400 cycles at 0.2 C,and a capacity of 633 mAhg−1 at a high current density of 3 C.This study presents an inspiring and promising strategy to fabricate emerging dual-functional separators,which paves the pathway for the practical implementation of ultra-stable and reliable Li-S battery systems.
基金support from the National Natural Science Foundation of China(22075042)the Natural Science Foundation of Shanghai(20ZR1401400)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Donghua University(DHU)Distinguished Young Professor Program(LZB2021002).
文摘Uncontrolled lithium dendrite growth hinders the practical application of lithium metal batteries(LMBs).Herein,we report a novel Li^(+) flux distributor achieved by placing an electroactive polyvinylidene fluoride/polymethyl methacrylate(PVDF/PMMA)composite nanofiber interlayer on a current collector,inducing uniform lithium deposition to mitigate the dendrite problem.Specifically,the released PMMA reacts with Liþto form abundant C–O–Li bonds and generate in situ a stable lithiophilic PMMA-Li solid electrolyte interphase layer.Theoretical calculations reveal that polar C–F groups in the PVDF framework and lithiophilic PMMA-Li provide homo-dispersed Li^(+) migration pathways with low energy barriers.Consequently,uniform Li nucleation is achieved at the molecular level,resulting in ultrahigh cycling stability with dendrite-free Li deposition at 5 mA cm^(-2) and 5 mAh cm^(-2)for over 500 h.The PVDF/PMMA||Li||LiFePO_(4)(LFP)full cell presents an increased rate capacity of 110 mAh g^(-1) at 10 C.In addition,a soft-package battery demonstrates a high energy density of 289 Wh kg^(-1).This work provides a facile design for stable lithium metal anodes to promote the practical use of LMBs and other alkali metal batteries.
