Based on annual statistical data collected by the Chinese Railway Statistic Center, the CO2 emissions of locomotives during 1975-2005 were calculated and the emission intensity and its dynamic characteristics were ana...Based on annual statistical data collected by the Chinese Railway Statistic Center, the CO2 emissions of locomotives during 1975-2005 were calculated and the emission intensity and its dynamic characteristics were analyzed. The results show that the CO2 emissions of steam locomotives decreased while that of diesel locomotives increased with time, due to the continuous shift from steam to diesel and electric locomotives. The total CO2 emissions of steam and diesel locomo- tives in China decreased from 42.23 Mt in 1975 to 16.40 Mt in 2005. The emission intensity of CO2 from the two kinds of locomotives decreased at an average rate of 2.4 g (converted t kin)-1 per year. The percentage of the CO2 emissions of locomotives to the total CO2 emissions in the sector of transportation, storage and post in China also decreased persistently from 1980 to 2005.展开更多
To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of...To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.展开更多
Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate obstacles.After spinal cord injury,stepping over an obstacle becomes challenging.Stepping over an obstacle requires senso...Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate obstacles.After spinal cord injury,stepping over an obstacle becomes challenging.Stepping over an obstacle requires sensorimotor transformations in several structures of the brain,including the parietal cortex,premotor cortex,and motor cortex.Sensory information and planning are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain balance.After spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including humans,fail to voluntarily modify limb trajectory to step over an obstacle.Therefore,in this review,we discuss the neuromechanical control of stepping over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.展开更多
Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail med...Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external excitations.In this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented.Further,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed.The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails.Execution of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal wear.This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.展开更多
Purpose–Auxiliary power system is an indispensable part of the train;the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways,which are either from auxiliary windings of t...Purpose–Auxiliary power system is an indispensable part of the train;the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways,which are either from auxiliary windings of traction transformers or from DC-link voltage of traction converters.Powered by DC-link voltage of traction converters,the auxiliary systems were maintained of uninterruptable power supply with energy from electric braking.Meanwhile,powered by traction transformers,the auxiliary systems were always out of power while passing the neutral section of power supply grid and control system is powered by battery at this time.Design/methodology/approach–Uninterrupted power supply of auxiliary power system powered by auxiliary winding of traction transformer was studied.Failure reasons why previous solutions cannot be realized are analyzed.An uninterruptable power supply scheme for the auxiliary systems powered by auxiliary windings of traction transformers is proposed in this paper.The validity of the proposed scheme is verified by simulation and experimental results and on-site operation of an upgraded HXD3C type locomotive.This scheme is attractive for upgrading practical locomotives with the auxiliary systems powered by auxiliary windings of traction transformers.Findings–This scheme regenerates braking power supplied to auxiliary windings of traction transformers while a locomotive runs in the neutral section of the power supply grid.Control objectives of uninterrupted power supply technology are proposed,which are no overvoltage,no overcurrent and uninterrupted power supply.Originality/value–The control strategies of the scheme ensure both overvoltage free and inrush current free when a locomotive enters or leaves the neutral section.Furthermore,this scheme is cost low by employing updated control strategy of software and add both the two current sensors and two connection wires of hardware.展开更多
Aim: This dissection study was conducted to verify if the Myofascial kinetic lines, outlined in detail in humans and recently documented in horses, were present in dogs. These dynamic lines present rows of interconnec...Aim: This dissection study was conducted to verify if the Myofascial kinetic lines, outlined in detail in humans and recently documented in horses, were present in dogs. These dynamic lines present rows of interconnected muscles, myofascia and other fascia structures, which influence the biomechanics of the spine and limbs. Methods: Forty-two dogs of different breeds and genders were dissected, imaged, and videoed. Results: Similar kinetic lines were verified in the dog, as described in humans and horses, and additionally, three new branches of the lines were discovered. The kinetic lines described were three superficial lines: Dorsal, Ventral, and Lateral, which all started in the hindlimb and ended in the temporal and occipital regions. These lines act respectively in spinal extension, flexion, and lateral flexion. Three profound lines, which started in the tail and ended in the head. The Deep Dorsal Line followed the transversospinal myofascia. The Deep Ventral Line showed an additional start deep in the medial hind limb, continued in the hypaxial myofascia, and enveloped all the viscera. Also, the Deep Lateral Line started in the hindlimb but parted along the trunk in the deep lateral myofascial structures. Two helical lines crossed the midline two or three times and served to rotate the spine. The Functional Line established a sling from the axilla to the contralateral stifle and presented a new ipsilateral branch. The Spiral Line connected the head and the ipsilateral tarsus and additionally presented a new straight branch. The four front limb lines describe their motion: the Front Limb Protraction and Retraction, Adduction, and Abduction Lines. Conclusion: The canine lines mirrored the equine and human lines with exceptions due to differences in anatomy, foot posture, lumbosacral flexibility, and their biomechanical constitution as predator versus prey animals. Additionally, three new canine branches were verified and described.展开更多
At cruising speed,one of the most significant contributing factors to train fuel consumption is aerodynamic drag,and the leading locomotive experiences much more drag than any other car in the train.This work reports ...At cruising speed,one of the most significant contributing factors to train fuel consumption is aerodynamic drag,and the leading locomotive experiences much more drag than any other car in the train.This work reports on the drag reduction that can be realized by the use of add-on nose fairings that are deployed on leading locomotives in a train set.Two types of fairing shapes were considered and all fairing walls are flat.It is anticipated that the fairing shapes would result from the deployment of easily stowed panels in an origami inspired manner.One of the fairing shapes has the appearance of a wedge and the other fairing is also wedge shaped,but with flow directing side wall features.For each general fairing shape,the important dimensions were parametrically varied in a systematic manner to identify the dimensions that yield maximum drag reduction.For the first shape,45 different scenarios were considered;for the second shape,15 were considered.A steady commercial computational fluid dynamic solver was employed to solve the flow field and locomotive drag for each of the scenarios.The best performing wedge-shaped fairing reduced the leading locomotive drag by nominally 14%and the best performing fairing shape with the side walls reduced the drag by 17%.展开更多
The spleen is critical for immunity.It is the largest immune organ and immune center in the peripheral system.While the relationship between behavior and immunity has been demonstrated in physiology and diseases,the r...The spleen is critical for immunity.It is the largest immune organ and immune center in the peripheral system.While the relationship between behavior and immunity has been demonstrated in physiology and diseases,the role of the spleen in behavior is not clear.To investigate the effects of the spleen on behaviors,we performed a refined splenectomy procedure on C57BL/6J mice and performed an open field test,circadian rhythm test,elevated plus maze,sucrose preference test,and Barnes maze test.Splenectomy did not induce changes in general locomotion,circadian rhythms,learning and memory,or depression/anxiety-related behaviors.To further investigate the effects of spleen on stress susceptibility,we established mouse models of depression through chronic unpredictable mild stress.The behavioral performances of mice subjected to splenectomy showed no differences from control animals.These findings suggest that splenectomy does not cause changes in baseline behavioral performance in mice.展开更多
Chx10-expressing V2 a(Chx10+V2 a) spinal interneurons play a large role in the excitatory drive of motoneurons. Chemogenetic ablation studies have demonstrated the essential nature of Chx10+V2 a interneurons in the re...Chx10-expressing V2 a(Chx10+V2 a) spinal interneurons play a large role in the excitatory drive of motoneurons. Chemogenetic ablation studies have demonstrated the essential nature of Chx10+V2 a interneurons in the regulation of locomotor initiation, maintenance, alternation, speed, and rhythmicity. The role of Chx10+V2 a interneurons in locomotion and autonomic nervous system regulation is thought to be robust, but their precise role in spinal motor regulation and spinal cord injury have not been fully explored. The present paper reviews the origin, characteristics, and functional roles of Chx10+V2 a interneurons with an emphasis on their involvement in the pathogenesis of spinal cord injury. The diverse functional properties of these cells have only been substantiated by and are due in large part to their integration in a variety of diverse spinal circuits. Chx10+V2 a interneurons play an integral role in conferring locomotion, which integrates various corticospinal, mechanosensory, and interneuron pathways. Moreover, accumulating evidence suggests that Chx10+V2 a interneurons also play an important role in rhythmic patterning maintenance, leftright alternation of central pattern generation, and locomotor pattern generation in higher order mammals, likely conferring complex locomotion. Consequently, the latest research has focused on postinjury transplantation and noninvasive stimulation of Chx10+V2 a interneurons as a therapeutic strategy, particularly in spinal cord injury. Finally, we review the latest preclinical study advances in laboratory derivation and stimulation/transplantation of these cells as a strategy for the treatment of spinal cord injury. The evidence supports that the Chx10+V2 a interneurons act as a new therapeutic target for spinal cord injury. Future optimization strategies should focus on the viability, maturity, and functional integration of Chx10+V2 a interneurons transplanted in spinal cord injury foci.展开更多
We previously found that monocyte locomotion inhibitory factor has a neuroprotective effect on ischemic brain injury during the acute phase of stro ke.Therefore,we modified the structure of an anti-inflammato ry monoc...We previously found that monocyte locomotion inhibitory factor has a neuroprotective effect on ischemic brain injury during the acute phase of stro ke.Therefore,we modified the structure of an anti-inflammato ry monocyte locomotion inhibitory factor peptide to construct an active cyclic peptide—Cyclo(MQCNS)(LZ-3)—and investigated its effects on ischemic stroke.In this study,we established a rat model of ischemic stroke by occluding the middle cerebral artery and then administered LZ-3(2 or 4 mg/kg) via the tail vein for 7 consecutive days.Our res ults showed that LZ-3(2 or 4 mg/kg) substantially decreased infarct volu m e,reduced co rtical ne rve cell death,improved neurological function,reduced cortical and hippocampal injury,and decreased the levels of inflammatory factors in the blood and brain tissues.In a well-diffe rentiated,oxygen-glucose deprivation/reoxygenation-induced BV2 cell model of poststroke,LZ-3(100 μM) inhibited the JAK1-STAT6 signaling pathway.LZ-3 regulated microglia/macrophage polarization from the M1 to the M2 type and inhibited microglia/macrophage phagocytosis and migration via the JAK1/STAT6 signaling pathway.To conclude,LZ-3 regulates microglial activation by inhibiting the JAK1/STAT6 sign aling pathway and improves functional recovery post-stroke.展开更多
Hand gesture recognition (HGR) is used in a numerous applications,including medical health-care, industrial purpose and sports detection.We have developed a real-time hand gesture recognition system using inertialsens...Hand gesture recognition (HGR) is used in a numerous applications,including medical health-care, industrial purpose and sports detection.We have developed a real-time hand gesture recognition system using inertialsensors for the smart home application. Developing such a model facilitatesthe medical health field (elders or disabled ones). Home automation has alsobeen proven to be a tremendous benefit for the elderly and disabled. Residentsare admitted to smart homes for comfort, luxury, improved quality of life,and protection against intrusion and burglars. This paper proposes a novelsystem that uses principal component analysis, linear discrimination analysisfeature extraction, and random forest as a classifier to improveHGRaccuracy.We have achieved an accuracy of 94% over the publicly benchmarked HGRdataset. The proposed system can be used to detect hand gestures in thehealthcare industry as well as in the industrial and educational sectors.展开更多
In the 16th and 17th century,Britain was constantly strained by sporadic plagues,famines,fires and political conflicts.As a response in literature,Shakespeare has constructed an annular locomotion paradigm in Fletcher...In the 16th and 17th century,Britain was constantly strained by sporadic plagues,famines,fires and political conflicts.As a response in literature,Shakespeare has constructed an annular locomotion paradigm in Fletcher and his collaboration work Cardenio.Be more specific,the locomotion routes can be exemplified in Möbius strip,a rhizome system,a reciprocating juxtaposition between the foreground and the background,either of which finally runs to an annular schema.The annular in narration corresponds with The Globe theater and the round world.Shakespeare may express his expectation and prospect for the uprising bourgeoise and the newly found world by the resurrection theme in literature.展开更多
Purpose–The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains,providing new insights and methods for their design and operation,thereby enhancing safety,ope...Purpose–The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains,providing new insights and methods for their design and operation,thereby enhancing safety,operational efficiency and track system design.Design/methodology/approach–A longitudinal dynamics simulation model of the super long heavy haul train was established and verified by the braking test data of 30,000 t heavy-haul combination train on the long and steep down grade of Daqing Line.The simulation model was used to analyze the influence of factors on the longitudinal force of super long heavy haul train.Findings–Under normal conditions,the formation length of extreme-long heavy-haul combined train has a small effect on the maximum longitudinal coupler force under full service braking and emergency braking on the straight line.The slope difference of the long and steep down grade has a great impact on the maximum longitudinal coupler force of the extreme-long heavy-haul trains.Under the condition that the longitudinal force does not exceed the safety limit of 2,250 kN under full service braking at the speed of 60 km/h the maximum allowable slope difference of long and steep down grade for 40,000 t super long heavy-haul combined trains is 13‰,and that of 100,000 t is only 5‰.Originality/value–The results will provide important theoretical basis and practical guidance for further improving the transportation efficiency and safety of extreme-long heavy-haul trains.展开更多
Purpose–The brake controller is a key component of the locomotive brake system.It is essential to study its safety.Design/methodology/approach–This paper summarizes and analyzes typical faults of the brake controlle...Purpose–The brake controller is a key component of the locomotive brake system.It is essential to study its safety.Design/methodology/approach–This paper summarizes and analyzes typical faults of the brake controller,and proposes four categories of faults:position sensor faults,microswitch faults,mechanical faults and communication faults.Suggestions and methods for improving the safety of the brake controller are also presented.Findings–In this paper,a self-judgment and self-learning dynamic calibration method is proposed,which integrates the linear error of the sensor and the manufacturing and assembly errors of the brake controller to solve the output drift.This paper also proposes a logic for diagnosing and handling microswitch faults.Suggestions are proposed for other faults of brake controller.Originality/value–The methods proposed in this paper can greatly improve the usability of the brake controller and reduce the failure rate.展开更多
To establish a universal and easily controlled gait for practical use of snakelike robot movement, an inchworm locomotion gait model based on a serpenoid curve is presented. By analyzing the relations of two adjacent ...To establish a universal and easily controlled gait for practical use of snakelike robot movement, an inchworm locomotion gait model based on a serpenoid curve is presented. By analyzing the relations of two adjacent waves in the process of locomotion and doing an approximation of the serpenoid curve, the motion function of relative angles between two adjacent links and the absolute angles between each link and the baseline on the traveling curve are built. Two efficiency criterions of the gait are given as the energy loss function f and the unit displacement in one cycle dunit.Three parameters of the criterions affecting the efficiency of the gait ( the number of links that form the traveling wave n, the included angle between two adjacent links α, and the phase difference of adjacent included angles β) are discussed by simulations and experiments. The results show that f is insensitive to n; raising n increases dunit significantly; the maximum wave amplitude of α is a decreasing function of n; and increasing α reduces the displacement influence off when n is determined. The gait model is suitable for different inchworm locomotions of a snakelike robot whose traveling waves are formed by different numbers of identical links. A wave formed by more links or a greater relative angle between two adjacent links both lead to greater velocity of the movement.展开更多
At present,Sri Lanka is home to about 5,000-6,000 wild elephants roaming over close to 70%of the country’s land.Despite this blessing,around 150 elephants die each year due to many reasons.The main reasons for the al...At present,Sri Lanka is home to about 5,000-6,000 wild elephants roaming over close to 70%of the country’s land.Despite this blessing,around 150 elephants die each year due to many reasons.The main reasons for the altercations between humans and elephants are the drastic increase in the human population,human encroachment upon elephant territory for agriculture and settlements and unplanned development and transportation efforts.Elephants are long lived herbivores,and their survival depends upon regular migration over large distances to search for food,water,and social and reproductive partners.According to the Sri Lanka railways the average number of elephants that get killed due to elephant-railway accidents is about 9 per year.As a solution for this problem,we have proposed a novel system to pass a signal to indicate the train arrival.The proposed system detects the vibration of the locomotives and after detecting the vibration,alarm system will generate a high frequency signal within the frequency range,where the elephants are sensitive.The proposed system is a low cost device and this can be placed anywhere at any time.Moreover,this project aims to protect elephants from being harmed which usually happen due to various human activities.展开更多
In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environm...In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments (enriched, social and isolated conditions). After 8 weeks, fear conditioning (characterized by percentage of freezing) was observed and analyzed, and rats' weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that: (1) Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; (2) Enriched and isolated conditions influenced rat's weight significantly; (3) Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.展开更多
Locomotion behaviors are susceptible to disruption by a broad spectrum of chemicals and environmental stresses. However, no systematic testing of locomotion behavior defects induced by metal exposure has been conducte...Locomotion behaviors are susceptible to disruption by a broad spectrum of chemicals and environmental stresses. However, no systematic testing of locomotion behavior defects induced by metal exposure has been conducted in the model organism of nematode Caenorhabditis elegans. In this study, the acute toxicity from heavy metal exposure on the locomotion behaviors was analyzed in nematodes. Endpoints of head thrash, body bend, forward turn, backward turn, and Omega/U turn were chosen to evaluate the locomotio...展开更多
Though the studies of wheel-legged robots have achieved great success, the existing ones still have defects in load distribution, structure stability and carrying capacity. For overcoming these shortcomings, a new kin...Though the studies of wheel-legged robots have achieved great success, the existing ones still have defects in load distribution, structure stability and carrying capacity. For overcoming these shortcomings, a new kind of wheel-legged robot(Rolling-Wolf) is designed. It is actuated by means of ball screws and sliders, and each leg forms two stable triangle structures at any moment, which is simple but has high structure stability. The positional posture model and statics model are built and used to analyze the kinematic and mechanical properties of Rolling-Wolf. Based on these two models, important indexes for evaluating its motion performance are analyzed. According to the models and indexes, all of the structure parameters which influence the motion performance of Rolling-Wolf are optimized by the method of Archive-based Micro Genetic Algorithm(AMGA) by using Isight and Matlab software. Compared to the initial values, the maximum rotation angle of the thigh is improved by 4.17%, the maximum lifting height of the wheel is improved by 65.53%, and the maximum driving forces of the thigh and calf are decreased by 25.5% and 12.58%, respectively. The conspicuous optimization results indicate that Rolling-Wolf is much more excellent. The novel wheel-leg structure of Rolling-Wolf is efficient in promoting the load distribution, structure stability and carrying capacity of wheel-legged robot and the proposed optimization method provides a new approach for structure optimization.展开更多
Objective:To investigate the effect of BMSCs transplantation plus hyperbaric oxygen(HBO)on repair of rat SCI.Methods:Seventy five male rats were divided randomly into five groups:sham,vehicle.BMSCs transplantation gro...Objective:To investigate the effect of BMSCs transplantation plus hyperbaric oxygen(HBO)on repair of rat SCI.Methods:Seventy five male rats were divided randomly into five groups:sham,vehicle.BMSCs transplantation group,combination group,15 rats in each group.Every week after the SCI onset,all animals were evaluated for behavior outcome by Basso-BeattleBresnahan(BBB) score and inclined plane test.Axon recovery was examined with focal spinal cord tissue by electron microscope at 6 weeks after the SCI onset.HE staining and BrdU staining were performed to examine the BMSCs and lesion post injury.Somatosensory evoked potential(SEP) testing was performed to detect the recovery of neural conduction.Results from the behavior tests from combination group were significant higher than rats which received only transplantation or HBO treatment.Results from histopathology showed favorable recovery from combination group than other treatment groups.The number of BrdU+ in combination group were measureable more than transplantation group(P<0.05).The greatest decrease in TNF-α,IL-1β,IL-6.IFN-α determined by Elisa assay in combination group were evident too.Conclusions:BMSCs transplantation can promote the functional recovery of rat hind limbs after SCI,and its combination with HBO has a synergistic effect.展开更多
文摘Based on annual statistical data collected by the Chinese Railway Statistic Center, the CO2 emissions of locomotives during 1975-2005 were calculated and the emission intensity and its dynamic characteristics were analyzed. The results show that the CO2 emissions of steam locomotives decreased while that of diesel locomotives increased with time, due to the continuous shift from steam to diesel and electric locomotives. The total CO2 emissions of steam and diesel locomo- tives in China decreased from 42.23 Mt in 1975 to 16.40 Mt in 2005. The emission intensity of CO2 from the two kinds of locomotives decreased at an average rate of 2.4 g (converted t kin)-1 per year. The percentage of the CO2 emissions of locomotives to the total CO2 emissions in the sector of transportation, storage and post in China also decreased persistently from 1980 to 2005.
基金Supported by National Natural Science Foundation of China (Grant Nos. 52375003, 52205006)National Key R&D Program of China (Grant No. 2019YFB1309600)。
文摘To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.
文摘Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate obstacles.After spinal cord injury,stepping over an obstacle becomes challenging.Stepping over an obstacle requires sensorimotor transformations in several structures of the brain,including the parietal cortex,premotor cortex,and motor cortex.Sensory information and planning are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain balance.After spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including humans,fail to voluntarily modify limb trajectory to step over an obstacle.Therefore,in this review,we discuss the neuromechanical control of stepping over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.
基金Supported by National Natural Science Foundation of China(Grant Nos.U2268210,52302474,52072249).
文摘Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external excitations.In this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented.Further,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed.The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails.Execution of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal wear.This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.
文摘Purpose–Auxiliary power system is an indispensable part of the train;the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways,which are either from auxiliary windings of traction transformers or from DC-link voltage of traction converters.Powered by DC-link voltage of traction converters,the auxiliary systems were maintained of uninterruptable power supply with energy from electric braking.Meanwhile,powered by traction transformers,the auxiliary systems were always out of power while passing the neutral section of power supply grid and control system is powered by battery at this time.Design/methodology/approach–Uninterrupted power supply of auxiliary power system powered by auxiliary winding of traction transformer was studied.Failure reasons why previous solutions cannot be realized are analyzed.An uninterruptable power supply scheme for the auxiliary systems powered by auxiliary windings of traction transformers is proposed in this paper.The validity of the proposed scheme is verified by simulation and experimental results and on-site operation of an upgraded HXD3C type locomotive.This scheme is attractive for upgrading practical locomotives with the auxiliary systems powered by auxiliary windings of traction transformers.Findings–This scheme regenerates braking power supplied to auxiliary windings of traction transformers while a locomotive runs in the neutral section of the power supply grid.Control objectives of uninterrupted power supply technology are proposed,which are no overvoltage,no overcurrent and uninterrupted power supply.Originality/value–The control strategies of the scheme ensure both overvoltage free and inrush current free when a locomotive enters or leaves the neutral section.Furthermore,this scheme is cost low by employing updated control strategy of software and add both the two current sensors and two connection wires of hardware.
文摘Aim: This dissection study was conducted to verify if the Myofascial kinetic lines, outlined in detail in humans and recently documented in horses, were present in dogs. These dynamic lines present rows of interconnected muscles, myofascia and other fascia structures, which influence the biomechanics of the spine and limbs. Methods: Forty-two dogs of different breeds and genders were dissected, imaged, and videoed. Results: Similar kinetic lines were verified in the dog, as described in humans and horses, and additionally, three new branches of the lines were discovered. The kinetic lines described were three superficial lines: Dorsal, Ventral, and Lateral, which all started in the hindlimb and ended in the temporal and occipital regions. These lines act respectively in spinal extension, flexion, and lateral flexion. Three profound lines, which started in the tail and ended in the head. The Deep Dorsal Line followed the transversospinal myofascia. The Deep Ventral Line showed an additional start deep in the medial hind limb, continued in the hypaxial myofascia, and enveloped all the viscera. Also, the Deep Lateral Line started in the hindlimb but parted along the trunk in the deep lateral myofascial structures. Two helical lines crossed the midline two or three times and served to rotate the spine. The Functional Line established a sling from the axilla to the contralateral stifle and presented a new ipsilateral branch. The Spiral Line connected the head and the ipsilateral tarsus and additionally presented a new straight branch. The four front limb lines describe their motion: the Front Limb Protraction and Retraction, Adduction, and Abduction Lines. Conclusion: The canine lines mirrored the equine and human lines with exceptions due to differences in anatomy, foot posture, lumbosacral flexibility, and their biomechanical constitution as predator versus prey animals. Additionally, three new canine branches were verified and described.
文摘At cruising speed,one of the most significant contributing factors to train fuel consumption is aerodynamic drag,and the leading locomotive experiences much more drag than any other car in the train.This work reports on the drag reduction that can be realized by the use of add-on nose fairings that are deployed on leading locomotives in a train set.Two types of fairing shapes were considered and all fairing walls are flat.It is anticipated that the fairing shapes would result from the deployment of easily stowed panels in an origami inspired manner.One of the fairing shapes has the appearance of a wedge and the other fairing is also wedge shaped,but with flow directing side wall features.For each general fairing shape,the important dimensions were parametrically varied in a systematic manner to identify the dimensions that yield maximum drag reduction.For the first shape,45 different scenarios were considered;for the second shape,15 were considered.A steady commercial computational fluid dynamic solver was employed to solve the flow field and locomotive drag for each of the scenarios.The best performing wedge-shaped fairing reduced the leading locomotive drag by nominally 14%and the best performing fairing shape with the side walls reduced the drag by 17%.
基金supported by the National Natural Science Foundation of China,Nos.81772438,81974357the Guangzhou Municipal Science and Technology Program,No.202206010197(all to YL)。
文摘The spleen is critical for immunity.It is the largest immune organ and immune center in the peripheral system.While the relationship between behavior and immunity has been demonstrated in physiology and diseases,the role of the spleen in behavior is not clear.To investigate the effects of the spleen on behaviors,we performed a refined splenectomy procedure on C57BL/6J mice and performed an open field test,circadian rhythm test,elevated plus maze,sucrose preference test,and Barnes maze test.Splenectomy did not induce changes in general locomotion,circadian rhythms,learning and memory,or depression/anxiety-related behaviors.To further investigate the effects of spleen on stress susceptibility,we established mouse models of depression through chronic unpredictable mild stress.The behavioral performances of mice subjected to splenectomy showed no differences from control animals.These findings suggest that splenectomy does not cause changes in baseline behavioral performance in mice.
基金supported by the National Natural Science Foundation of China,No. 81870977 (to YW)the Natural Science Foundation of Heilongjiang Province of China,No. JQ2021H004 (to YW)+1 种基金PhD research foundation of Mudanjiang Medicine College,No. 2021-MYBSKY-039 (to WYL)Fundamental Research Funds for Heilongjiang Provincial Universities,No. 2021-KYYWF-0469 (to WYL)。
文摘Chx10-expressing V2 a(Chx10+V2 a) spinal interneurons play a large role in the excitatory drive of motoneurons. Chemogenetic ablation studies have demonstrated the essential nature of Chx10+V2 a interneurons in the regulation of locomotor initiation, maintenance, alternation, speed, and rhythmicity. The role of Chx10+V2 a interneurons in locomotion and autonomic nervous system regulation is thought to be robust, but their precise role in spinal motor regulation and spinal cord injury have not been fully explored. The present paper reviews the origin, characteristics, and functional roles of Chx10+V2 a interneurons with an emphasis on their involvement in the pathogenesis of spinal cord injury. The diverse functional properties of these cells have only been substantiated by and are due in large part to their integration in a variety of diverse spinal circuits. Chx10+V2 a interneurons play an integral role in conferring locomotion, which integrates various corticospinal, mechanosensory, and interneuron pathways. Moreover, accumulating evidence suggests that Chx10+V2 a interneurons also play an important role in rhythmic patterning maintenance, leftright alternation of central pattern generation, and locomotor pattern generation in higher order mammals, likely conferring complex locomotion. Consequently, the latest research has focused on postinjury transplantation and noninvasive stimulation of Chx10+V2 a interneurons as a therapeutic strategy, particularly in spinal cord injury. Finally, we review the latest preclinical study advances in laboratory derivation and stimulation/transplantation of these cells as a strategy for the treatment of spinal cord injury. The evidence supports that the Chx10+V2 a interneurons act as a new therapeutic target for spinal cord injury. Future optimization strategies should focus on the viability, maturity, and functional integration of Chx10+V2 a interneurons transplanted in spinal cord injury foci.
文摘We previously found that monocyte locomotion inhibitory factor has a neuroprotective effect on ischemic brain injury during the acute phase of stro ke.Therefore,we modified the structure of an anti-inflammato ry monocyte locomotion inhibitory factor peptide to construct an active cyclic peptide—Cyclo(MQCNS)(LZ-3)—and investigated its effects on ischemic stroke.In this study,we established a rat model of ischemic stroke by occluding the middle cerebral artery and then administered LZ-3(2 or 4 mg/kg) via the tail vein for 7 consecutive days.Our res ults showed that LZ-3(2 or 4 mg/kg) substantially decreased infarct volu m e,reduced co rtical ne rve cell death,improved neurological function,reduced cortical and hippocampal injury,and decreased the levels of inflammatory factors in the blood and brain tissues.In a well-diffe rentiated,oxygen-glucose deprivation/reoxygenation-induced BV2 cell model of poststroke,LZ-3(100 μM) inhibited the JAK1-STAT6 signaling pathway.LZ-3 regulated microglia/macrophage polarization from the M1 to the M2 type and inhibited microglia/macrophage phagocytosis and migration via the JAK1/STAT6 signaling pathway.To conclude,LZ-3 regulates microglial activation by inhibiting the JAK1/STAT6 sign aling pathway and improves functional recovery post-stroke.
基金supported by a grant (2021R1F1A1063634)of the Basic Science Research Program through the National Research Foundation (NRF)funded by the Ministry of Education,Republic of Korea.
文摘Hand gesture recognition (HGR) is used in a numerous applications,including medical health-care, industrial purpose and sports detection.We have developed a real-time hand gesture recognition system using inertialsensors for the smart home application. Developing such a model facilitatesthe medical health field (elders or disabled ones). Home automation has alsobeen proven to be a tremendous benefit for the elderly and disabled. Residentsare admitted to smart homes for comfort, luxury, improved quality of life,and protection against intrusion and burglars. This paper proposes a novelsystem that uses principal component analysis, linear discrimination analysisfeature extraction, and random forest as a classifier to improveHGRaccuracy.We have achieved an accuracy of 94% over the publicly benchmarked HGRdataset. The proposed system can be used to detect hand gestures in thehealthcare industry as well as in the industrial and educational sectors.
基金Chongqing Social Science Fund Project“The Ethical Topology of Shakespeare’s Histories”(2020WYZX07).
文摘In the 16th and 17th century,Britain was constantly strained by sporadic plagues,famines,fires and political conflicts.As a response in literature,Shakespeare has constructed an annular locomotion paradigm in Fletcher and his collaboration work Cardenio.Be more specific,the locomotion routes can be exemplified in Möbius strip,a rhizome system,a reciprocating juxtaposition between the foreground and the background,either of which finally runs to an annular schema.The annular in narration corresponds with The Globe theater and the round world.Shakespeare may express his expectation and prospect for the uprising bourgeoise and the newly found world by the resurrection theme in literature.
基金subsidized by CHINA RAILWAY Scientific and Technological Research and Development Project(No.2018J008)CHN ENERGY Investment Group Co.,LTD(No.GJNY-20-232),to which,the authors hereby express our appreciation.
文摘Purpose–The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains,providing new insights and methods for their design and operation,thereby enhancing safety,operational efficiency and track system design.Design/methodology/approach–A longitudinal dynamics simulation model of the super long heavy haul train was established and verified by the braking test data of 30,000 t heavy-haul combination train on the long and steep down grade of Daqing Line.The simulation model was used to analyze the influence of factors on the longitudinal force of super long heavy haul train.Findings–Under normal conditions,the formation length of extreme-long heavy-haul combined train has a small effect on the maximum longitudinal coupler force under full service braking and emergency braking on the straight line.The slope difference of the long and steep down grade has a great impact on the maximum longitudinal coupler force of the extreme-long heavy-haul trains.Under the condition that the longitudinal force does not exceed the safety limit of 2,250 kN under full service braking at the speed of 60 km/h the maximum allowable slope difference of long and steep down grade for 40,000 t super long heavy-haul combined trains is 13‰,and that of 100,000 t is only 5‰.Originality/value–The results will provide important theoretical basis and practical guidance for further improving the transportation efficiency and safety of extreme-long heavy-haul trains.
基金supported by the China Academy of Railway Sciences Foundation[Grant No.2021YJ244].
文摘Purpose–The brake controller is a key component of the locomotive brake system.It is essential to study its safety.Design/methodology/approach–This paper summarizes and analyzes typical faults of the brake controller,and proposes four categories of faults:position sensor faults,microswitch faults,mechanical faults and communication faults.Suggestions and methods for improving the safety of the brake controller are also presented.Findings–In this paper,a self-judgment and self-learning dynamic calibration method is proposed,which integrates the linear error of the sensor and the manufacturing and assembly errors of the brake controller to solve the output drift.This paper also proposes a logic for diagnosing and handling microswitch faults.Suggestions are proposed for other faults of brake controller.Originality/value–The methods proposed in this paper can greatly improve the usability of the brake controller and reduce the failure rate.
文摘To establish a universal and easily controlled gait for practical use of snakelike robot movement, an inchworm locomotion gait model based on a serpenoid curve is presented. By analyzing the relations of two adjacent waves in the process of locomotion and doing an approximation of the serpenoid curve, the motion function of relative angles between two adjacent links and the absolute angles between each link and the baseline on the traveling curve are built. Two efficiency criterions of the gait are given as the energy loss function f and the unit displacement in one cycle dunit.Three parameters of the criterions affecting the efficiency of the gait ( the number of links that form the traveling wave n, the included angle between two adjacent links α, and the phase difference of adjacent included angles β) are discussed by simulations and experiments. The results show that f is insensitive to n; raising n increases dunit significantly; the maximum wave amplitude of α is a decreasing function of n; and increasing α reduces the displacement influence off when n is determined. The gait model is suitable for different inchworm locomotions of a snakelike robot whose traveling waves are formed by different numbers of identical links. A wave formed by more links or a greater relative angle between two adjacent links both lead to greater velocity of the movement.
文摘At present,Sri Lanka is home to about 5,000-6,000 wild elephants roaming over close to 70%of the country’s land.Despite this blessing,around 150 elephants die each year due to many reasons.The main reasons for the altercations between humans and elephants are the drastic increase in the human population,human encroachment upon elephant territory for agriculture and settlements and unplanned development and transportation efforts.Elephants are long lived herbivores,and their survival depends upon regular migration over large distances to search for food,water,and social and reproductive partners.According to the Sri Lanka railways the average number of elephants that get killed due to elephant-railway accidents is about 9 per year.As a solution for this problem,we have proposed a novel system to pass a signal to indicate the train arrival.The proposed system detects the vibration of the locomotives and after detecting the vibration,alarm system will generate a high frequency signal within the frequency range,where the elephants are sensitive.The proposed system is a low cost device and this can be placed anywhere at any time.Moreover,this project aims to protect elephants from being harmed which usually happen due to various human activities.
基金National Natural Science Foundation of China(30770689)Scientific Research Fund of Hunan Provincial Education Department (05B045)National Basic Research Program of China (2002CB410803-04)
文摘In the present experiment, Pavlovian fear conditioning was adopted to study the effects of different early rearing environments on fear conditioning in adult rats. Weaned rats were reared in three manipulable environments (enriched, social and isolated conditions). After 8 weeks, fear conditioning (characterized by percentage of freezing) was observed and analyzed, and rats' weight, locomoter activity and foot-shock sensitivity were operated too. The results showed that: (1) Compared with control group, the level of conditioned fear was significantly increased in enriched group, but significantly decreased in isolated group; (2) Enriched and isolated conditions influenced rat's weight significantly; (3) Different rearing conditions have no effect on locomoter activity and foot-shock sensitivity. These results indicated that early enriched condition could improve the tone-evoked fear conditioning response, while isolated condition impaired the response.
基金the Southeast Uni-versity Foundation for Excellent Young Scholars (No.4023001013)the NIH,National Center for Foundation from Research Resource,USA
文摘Locomotion behaviors are susceptible to disruption by a broad spectrum of chemicals and environmental stresses. However, no systematic testing of locomotion behavior defects induced by metal exposure has been conducted in the model organism of nematode Caenorhabditis elegans. In this study, the acute toxicity from heavy metal exposure on the locomotion behaviors was analyzed in nematodes. Endpoints of head thrash, body bend, forward turn, backward turn, and Omega/U turn were chosen to evaluate the locomotio...
基金Supported by National Hi-tech Research and Development Program of China (863 Program,Grant No.CDJZR13110073)
文摘Though the studies of wheel-legged robots have achieved great success, the existing ones still have defects in load distribution, structure stability and carrying capacity. For overcoming these shortcomings, a new kind of wheel-legged robot(Rolling-Wolf) is designed. It is actuated by means of ball screws and sliders, and each leg forms two stable triangle structures at any moment, which is simple but has high structure stability. The positional posture model and statics model are built and used to analyze the kinematic and mechanical properties of Rolling-Wolf. Based on these two models, important indexes for evaluating its motion performance are analyzed. According to the models and indexes, all of the structure parameters which influence the motion performance of Rolling-Wolf are optimized by the method of Archive-based Micro Genetic Algorithm(AMGA) by using Isight and Matlab software. Compared to the initial values, the maximum rotation angle of the thigh is improved by 4.17%, the maximum lifting height of the wheel is improved by 65.53%, and the maximum driving forces of the thigh and calf are decreased by 25.5% and 12.58%, respectively. The conspicuous optimization results indicate that Rolling-Wolf is much more excellent. The novel wheel-leg structure of Rolling-Wolf is efficient in promoting the load distribution, structure stability and carrying capacity of wheel-legged robot and the proposed optimization method provides a new approach for structure optimization.
基金supported by a grant from Yun Nan province united foundation(2008CD006)Yun Nan province education department foundation(2011y184)
文摘Objective:To investigate the effect of BMSCs transplantation plus hyperbaric oxygen(HBO)on repair of rat SCI.Methods:Seventy five male rats were divided randomly into five groups:sham,vehicle.BMSCs transplantation group,combination group,15 rats in each group.Every week after the SCI onset,all animals were evaluated for behavior outcome by Basso-BeattleBresnahan(BBB) score and inclined plane test.Axon recovery was examined with focal spinal cord tissue by electron microscope at 6 weeks after the SCI onset.HE staining and BrdU staining were performed to examine the BMSCs and lesion post injury.Somatosensory evoked potential(SEP) testing was performed to detect the recovery of neural conduction.Results from the behavior tests from combination group were significant higher than rats which received only transplantation or HBO treatment.Results from histopathology showed favorable recovery from combination group than other treatment groups.The number of BrdU+ in combination group were measureable more than transplantation group(P<0.05).The greatest decrease in TNF-α,IL-1β,IL-6.IFN-α determined by Elisa assay in combination group were evident too.Conclusions:BMSCs transplantation can promote the functional recovery of rat hind limbs after SCI,and its combination with HBO has a synergistic effect.