This study investigated the validity and sensitivity of a custom-made shoelace tensile testing system.The aim was to analyze the distribution pattern of shoelace tension in different positions and under different tigh...This study investigated the validity and sensitivity of a custom-made shoelace tensile testing system.The aim was to analyze the distribution pattern of shoelace tension in different positions and under different tightness levels during running.Mechanical tests were conducted using 16 weights,and various statistical analyses,including linear regression,Bland-Altman plots,coefficient of variation,and intraclass correlation coefficient,were performed to assess the system’s validity.Fifteen male amateur runners participated in the study,and three conditions(loose,comfortable,and tight)were measured during an upright stance.The system utilized VICON motion systems,a Kistler force plate,and a Photoelectric gate speed measurement system.Results showed a linear relationship between voltage and load at the three sensors(R2≥0.9997).Bland-Altman plots demonstrated 95%prediction intervals within±1.96SD from zero for all sensors.The average coefficient of variation for each sensor was less than 0.38%.Intraclass correlation coefficient values were larger than 0.999(p<0.0001)for each sensor.The peak tension of the front shoelace was greater than that of the front and middle when the shoelace was loose and tight.The rear shoelace had the highest tension force.The study also found that shoelace tension varied throughout the gait cycle during running.Overall,this research provides a novel and validated method for measuring shoelace tensile stress,which has implications for developing automatic shoelace fastening systems.展开更多
The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and run...The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.展开更多
Purpose We aimed to investigate the effects of running shoe longitudinal bending stiffness(LBS)and midsole energy return on running economy and ankle mechanics and energetics.Methods PubMed,Scopus,SPORTDiscus,Embase,C...Purpose We aimed to investigate the effects of running shoe longitudinal bending stiffness(LBS)and midsole energy return on running economy and ankle mechanics and energetics.Methods PubMed,Scopus,SPORTDiscus,Embase,CINAHL,and Web of Science were systematically searched for this meta-analysis.Crossover studies comparing the effects of running shoe LBS and/or midsole energy return on at least 1 of the following outcomes:running economy,ankle plantarflexion moment,work,power,or angular velocity were included.Results Of the 2453 studies screened,48 were included(n=878).Results indicated that advanced footwear technologies(AFTs)significantly reduced oxygen consumption(standardized mean difference=–0.44,95%confidence interval:–0.60 to–0.28),p<0.001)as well as peak ankle moments and positive/negative ankle work and power.However,neither LBS nor midsole energy return alone significantly affected oxygen consumption,ankle moments,positive and negative work,or positive power.The effects of AFTs were moderated by the training status and speed of the runner.The quality of evidence for all outcomes were low or very low for all outcomes except the effect of LBS on negative ankle work.Conclusion AFT may improve running economy by minimizing ankle moments,work,and power.The absence of significant independent effects of LBS and midsole energy return suggests that the benefits of AFTs arise from the interaction of these properties.Further research is necessary to understand the mechanisms for improved running performance in AFTs.展开更多
The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by 2024.However,the aforementioned goal is challenged by households that are scattered in re...The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by 2024.However,the aforementioned goal is challenged by households that are scattered in remote areas.So far,Solar Home Systems(SHS)have mostly been applied to increase electricity access in rural areas.SHSs have continuous constraints to meet electricity demands and cannot run income-generating activities.The current research presents the feasibility study of electrifying Remera village with the smart microgrid as a case study.The renewable energy resources available in Remera are the key sources of electricity in that village.The generation capacity is estimated based on the load profile.The microgrid configurations are simulated with HOMER,and the genetic algorithm is used to analyze the optimum cost.By analyzing the impact of operation and maintenance costs,the results show that the absence of subsidies increases the levelized cost of electricity(COE)five times greater than the electricity price from the public utility.The microgrid made up of PV,diesel generator,and batteries proved to be the most viable solution and ensured continuous power supply to customers.By considering the subsidies,COE reaches 0.186$/kWh,a competitive price with electricity from public utilities in Rwanda.展开更多
Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can b...Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.展开更多
Spinal cord injury necessitates effective rehabilitation strategies, with exercise therapies showing promise in promoting recovery. This study investigated the impact of rehabilitation exercise on functional recovery ...Spinal cord injury necessitates effective rehabilitation strategies, with exercise therapies showing promise in promoting recovery. This study investigated the impact of rehabilitation exercise on functional recovery and morphological changes following thoracic contusive spinal cord injury. After a 7-day recovery period after spinal cord injury, mice were assigned to either a trained group(10 weeks of voluntary running wheel or forced treadmill exercise) or an untrained group. Bi-weekly assessments revealed that the exercise-trained group, particularly the voluntary wheel exercise subgroup, displayed significantly improved locomotor recovery, more plasticity of dopaminergic and serotonin modulation compared with the untrained group. Additionally, exercise interventions led to gait pattern restoration and enhanced transcranial magnetic motor-evoked potentials. Despite consistent injury areas across groups, exercise training promoted terminal innervation of descending axons. In summary, voluntary wheel exercise shows promise for enhancing outcomes after thoracic contusive spinal cord injury, emphasizing the role of exercise modality in promoting recovery and morphological changes in spinal cord injuries. Our findings will influence future strategies for rehabilitation exercises, restoring functional movement after spinal cord injury.展开更多
Urban environments offer a wealth of opportunities for residents to respite from their hectic life.Outdoor running or jogging becomes increasingly popular of an option.Impacts of urban environments on outdoor running,...Urban environments offer a wealth of opportunities for residents to respite from their hectic life.Outdoor running or jogging becomes increasingly popular of an option.Impacts of urban environments on outdoor running,despite some initial studies,remain underexplored.This study aims to establish an analytical framework that can holistically assess the urban environment on the healthy vitality of running.The proposed framework is applied to two modern Chinese cities,i.e.,Guangzhou and Shenzhen.We construct three interpretable random forest models to explore the non-linear relationship between environmental variables and running intensity(RI)through analyzing the runners'trajectories and integrating with multi-source urban big data(e.g.,street view imagery,remote sensing,and socio-economic data)across the built,natural,and social dimensions,The findings uncover that road density has the greatest impact on RI,and social variables(e.g.,population density and housing price)and natural variables(e.g.,slope and humidity)all make notable impact on outdoor running.Despite these findings,the impact of environmental variables likely change across different regions due to disparate regional construction and micro-environments,and those specific impacts as well as optimal thresholds also alter.Therefore,construction of healthy cities should take the whole urban environment into account and adapt to local conditions.This study provides a comprehensive evaluation on the influencing variables of healthy vitality and guides sustainable urban planning for creating running-friendly cities.展开更多
Objective:Running-related musculoskeletal injuries(RRMIs),especially stemming from overuse,frequently occur in runners.This study aimed to systematically review the literature and determine the incidence and prevalenc...Objective:Running-related musculoskeletal injuries(RRMIs),especially stemming from overuse,frequently occur in runners.This study aimed to systematically review the literature and determine the incidence and prevalence proportion of RRMIs by anatomic location and specific pathology.Methods:An electronic database search with no date beginning restrictions was performed in SPORTDiscus,PubMed,and MEDLINE up to June 2020.Prospective studies were used to find the anatomic location and the incidence proportion of each RRMI,whereas retrospective or cross-sectional studies were used to find the prevalence proportion of each RRMI.A separate analysis for ultramarathon runners was performed.Results:The overall injury incidence and prevalence were 40.2%±18.8%and 44.6%±18.4%(mean±SD),respectively.The knee,ankle,and lower leg accounted for the highest proportion of injury incidence,whereas the knee,lower leg,and foot/toes had the highest proportion of injury prevalence.Achilles tendinopathy(10.3%),medial tibial stress syndrome(9.4%),patellofemoral pain syndrome(6.3%),plantar fasciitis(6.1%),and ankle sprains(5.8%)accounted for the highest proportion of injury incidence,whereas patellofemoral pain syndrome(16.7%),medial tibial stress syndrome(9.1%),plantar fasciitis(7.9%),iliotibial band syndrome(7.9%),and Achilles tendinopathy(6.6%)had the highest proportion of injury prevalence.The ankle(34.5%),knee(28.1%),and lower leg(12.9%)were the 3 most frequently injured sites among ultramarathoners.Conclusion:The injury incidence proportions by anatomic location between ultramarathoners and non-ultramarathoners were not significantly different(p=0.798).The pathologies with the highest incidence proportion of injuries were anterior compartment tendinopathy(19.4%),patellofemoral pain syndrome(15.8%),and Achilles tendinopathy(13.7%).The interpretation of epidemiological data in RRMIs is limited due to several methodological issues encountered.展开更多
Dynamic running law of the hydraulic driving system decides the hoisting cage velocity curve in a hoisting cycle and is decided by the characteristic of the hydraulic driving system and by the operating speed of hoist...Dynamic running law of the hydraulic driving system decides the hoisting cage velocity curve in a hoisting cycle and is decided by the characteristic of the hydraulic driving system and by the operating speed of hoist driver. The paper studies the dynamic running law of hydraulic driving system, analyses the influence of driver operating speed on the dynamic running characteristic, and points out the reasonable driver operating speed to control the dynamic stress in rope and to reduce the oscillation of rope system.展开更多
An integrated monitoring system for running parameters of key mining equipmenton the basis of condition monitoring technology and modern communication networktechnology was developed.The system consists of a client co...An integrated monitoring system for running parameters of key mining equipmenton the basis of condition monitoring technology and modern communication networktechnology was developed.The system consists of a client computer with functions ofsignal acquisition and processing, and a host computer in the central control room.Thesignal acquisition module of the client computer can collect the running parameters fromvarious monitoring terminals in real-time.The DSP high-speed data processing system ofthe main control module can quickly achieve the numerical calculation for the collectedsignal.The signal modulation and signal demodulation are completed by the frequencyshift keying circuit and phase-locked loop frequency circuit, respectively.Finally, the signalis sent to the host computer for logic estimation and diagnostic analysis using the networkcommunication technology, which is helpful for technicians and managers to control therunning state of equipment.展开更多
Background:Foot kinematics,such as excessive eversion and malalignment of the hindfoot,are believed to be associated with running-related injuries.The maj ority of studies to date show that different foot strike patte...Background:Foot kinematics,such as excessive eversion and malalignment of the hindfoot,are believed to be associated with running-related injuries.The maj ority of studies to date show that different foot strike patterns influence these specific foot and ankle kinematics.However,technical deficiencies in traditional motion capture approaches limit knowledge of in vivo joint kinematics with respect to rearfoot and forefoot strike patterns(RFS and FFS,respectively).This study uses a high-speed dual fluoroscopic imaging system(DFIS)to determine the effects of different foot strike patterns on 3D in vivo tibiotalar and subtalar joints kinematics.Methods:Fifteen healthy male recreational runners underwent foot computed tomography scanning for the construction of 3-dimensional models.A high-speed DFIS(100 Hz)was used to collect 6 degrees of freedom kinematics for participants’tibiotalar and subtalar joints when they adopted RFS and FFS in barefoot condition.Results:Compared with RFS,FFS exhibited greater internal rotation at 0%-20%of the stance phase in the tibiotalar joint.The peak internal rotation angle of the tibiotalar joint under FFS was greater than under RFS(p<0.001,Cohen’s d=0.92).RFS showed more dorsiflexion at 0%-20%of the stance phase in the tibiotalar joint than FFS.RFS also presented a larger anterior translation(p<0.001,Cohen’s d=1.28)in the subtalar joint at i nitial contact than FFS.Conclusion:Running with acute barefoot FFS increases the internal rotation of the tibiotalar joint in the early stance.The use of high-speed DFIS to quantify the movement of the tibiotalar and subtalar joint was critical to revealing the effects of RF S and FFS during running.展开更多
Exercise training is critical for the early prevention and treatment of obesity and diabetes mellitus.However,the mechanism with gut microbiota and fecal metabolites underlying the effects of voluntary wheel running o...Exercise training is critical for the early prevention and treatment of obesity and diabetes mellitus.However,the mechanism with gut microbiota and fecal metabolites underlying the effects of voluntary wheel running on high-fat diet induced abnormal glucose metabolism has not been fully elaborated.C57BL/6 male mice were randomly assigned to 4 groups according to diets(fed with normal chow diet or high-fat diet)and running paradigm(housed in static cage or with voluntary running wheel).An integrative 16S rDNA sequencing and metabolites profiling was synchronously performed to characterize the effects of voluntary wheel running on gut microbiota and metabolites.It showed that voluntary wheel running prevented the detrimental effects of high-fat feeding on glucose metabolism 16S rDNA sequencing showed remarkable changes in Rikenella and Marvinbryantia genera.Metabolic profiling indicated multiple altered metabolites,which were enriched in secondary bile acid biosynthesis signaling.In conclusion,our study indicated that voluntary wheel running significantly improved glucose metabolism and counteracted the deleterious effects of high-fat feeding on body weight and glucose intolerance.We further found that voluntary wheel running could integratively program gut microbiota composition and fecal metabolites changes,and may regulate muricholic acid metabolism and secondary bile acid biosynthesis in high-fat fed mice.展开更多
Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper...Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.展开更多
Purpose This study aimed to investigate whether there is a systematic change of leg muscle activity,as quantified by surface electromyography(EMG),throughout a standard running footwear assessment protocol at a predet...Purpose This study aimed to investigate whether there is a systematic change of leg muscle activity,as quantified by surface electromyography(EMG),throughout a standard running footwear assessment protocol at a predetermined running speed.Methods Thirty-one physically active adults(15 females and 16 males)completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s.The level of muscle activity from 6 major leg muscles was recorded using surface EMG.The variables assessed were the EMG total intensity as a function of time and the cumulative EMG overall intensity.Systematic effects of the chronological testing round(independent variable)on the normalized EMG overall intensity(dependent variable)were examined using Friedman analysis of variates and post hoc pairwise Wilcoxon signed-rank tests(α=0.05).Results There was a systematic reduction in overall EMG intensity for all 6 muscles over the time course of the running protocol(p<0.001)until the fourth testing round when EMG intensities reached a steady state.The one exception was the biceps femoris muscle,which showed a significant reduction of EMG intensity during the stance phase(p<0.001)but not the swing phase(p=0.16).Conclusion While running at a predetermined speed,the neuromuscular system undergoes an adaptation process characterized by a progressive reduction in the activity level of major leg muscles.This process may represent an optimization strategy of the neuromuscular system towards a more energetically efficient running style.Future running protocols should include a familiarization period of at least 7 min or 600 strides of running at the predetermined speed.展开更多
Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter＇ s security and other performance capabilitie...Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter＇ s security and other performance capabilities. In testing, however, it has been difficult to measure the elevation when the rotor reaches high speeds. To get a simple, fast and highly accurate measurement system, photo electricity technology was applied to measuring the blade running elevation. Discussed is the measurement principle of blade running elevation, tire design of the measurement system and analysis of the measurement precision.展开更多
Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a ...Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a pandemic.The use of face masks and respirators is an important public health measure to reduce or prevent transmission of SARS-CoV-2.Here we discuss the hypothetical mechanisms by which exercise with face masks or respirators can induce detrimental effects on the cardiovascular system,potentially explaining adverse events such as cardiac arrhythmias and spontaneous pneumothorax.Although sudden death associated with the wearing of a face mask during running is a rare event,the risk is higher especially in those with existing cardiac comorbidities.In such cases,a mask designed specifi cally for runners with no or few side effects of oxygen defi ciency should be considered instead.展开更多
The accurate assessment of running safety during earthquakes is of significant importance for ensuring the safety of railway lines.Currently,assessment methods based on a single index suffer from issues such as misjud...The accurate assessment of running safety during earthquakes is of significant importance for ensuring the safety of railway lines.Currently,assessment methods based on a single index suffer from issues such as misjudgment of operational safety and difficulty in evaluating operational margin,making them unsuitable for assessing train safety during earthquakes.Therefore,in order to propose an effective evaluation method for the running safety of trains during earthquakes,this study employs three indexes,namely lateral displacement of the wheel–rail contact point,wheel unloading rate,and wheel lift,to describe the lateral and vertical contact states between the wheel and rail.The corresponding evolution characteristics of the wheel–rail contact states are determined,and the derailment forms under different frequency components of seismic motion are identified through dynamic numerical simulations of the train–track coupled system under sine excitation.The variations in the wheel–rail contact states during the transition from a safe state to the critical state of derailment are analyzed,thereby constructing the evolutionary path of train derailment and seismic derailment risk domain.Lastly,the wheel–rail contact and derailment states under seismic conditions are analyzed,thus verifying the effectiveness of the evaluation method for assessing running safety under earthquakes proposed in this study.The results indicate that the assessment method based on the derailment risk domain accurately and comprehensively reflects the wheel–rail contact states under seismic conditions.It successfully determines the forms of train derailment,the risk levels of derailment,and the evolutionary paths of derailment risk.展开更多
Purpose-Express freight transportation is in rapid development currently.Owing to the higher speed of express freight train,the deformation of the bridge deck worsens the railway line condition under the action of win...Purpose-Express freight transportation is in rapid development currently.Owing to the higher speed of express freight train,the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge.Besides,the blunt car body of vehicle has poor aerodynamic characteristics,bringing a greater challenge on the running stability in the crosswind.Design/methodology/approach-In this study,the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test.The dynamic model of the train-long-span steel truss bridge coupling system is established,and the dynamic response as well as the running safety of vehicle are evaluated.Findings-The results show that wind speed has a significant influence on running safety,which is mainly reflected in the over-limitation of wheel unloading rate.The wind speed limit decreases with train speed,and it reduces to 18.83 m/s when the train speed is 160 km/h.Originality/value-This study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems.It also provides a new theoretical basis for the safety assessment of express freight trains.展开更多
In order to convey complete meanings,there is a phenomenon in Chinese of using multiple running sentences.Xu Jingning(2023,p.66)states,“In communication,a complete expression of meaning often requires more than one c...In order to convey complete meanings,there is a phenomenon in Chinese of using multiple running sentences.Xu Jingning(2023,p.66)states,“In communication,a complete expression of meaning often requires more than one clause,which is common in human languages.”Domestic research on running sentences includes discussions on defining the concept and structural features of running sentences,sentence properties,sentence pattern classifications and their criteria,as well as issues related to translating running sentences into English.This article primarily focuses on scholarly research into the English translation of running sentences in China,highlighting recent achievements and identifying existing issues in the study of running sentence translation.However,by reviewing literature on the translation of running sentences,it is found that current research in the academic community on non-core running sentences is limited.Therefore,this paper proposes relevant strategies to address this issue.展开更多
A real-life milk run system designing problem of an engine manufacturer adopted JIT(just-in-time)production is studied.In the process of milk run system planning and design,the supply base is identified and a supplier...A real-life milk run system designing problem of an engine manufacturer adopted JIT(just-in-time)production is studied.In the process of milk run system planning and design,the supply base is identified and a supplier site map is plotted for an arrangement of routes on which parts are periodically collected in a JIT manner from many scattered suppliers.With unit load designing,vehicle choosing and fleet sizing,pickup routing,vehicle assigning and scheduling problems are studied.Among these problems,a CVRP problem is identified and formulated as the key optimization in designing this milk run system,and it is solved through an optimization process.This tactical planning and optimization process gives a good solution to the real problem,and may shed light on the planning of similar systems.展开更多
文摘This study investigated the validity and sensitivity of a custom-made shoelace tensile testing system.The aim was to analyze the distribution pattern of shoelace tension in different positions and under different tightness levels during running.Mechanical tests were conducted using 16 weights,and various statistical analyses,including linear regression,Bland-Altman plots,coefficient of variation,and intraclass correlation coefficient,were performed to assess the system’s validity.Fifteen male amateur runners participated in the study,and three conditions(loose,comfortable,and tight)were measured during an upright stance.The system utilized VICON motion systems,a Kistler force plate,and a Photoelectric gate speed measurement system.Results showed a linear relationship between voltage and load at the three sensors(R2≥0.9997).Bland-Altman plots demonstrated 95%prediction intervals within±1.96SD from zero for all sensors.The average coefficient of variation for each sensor was less than 0.38%.Intraclass correlation coefficient values were larger than 0.999(p<0.0001)for each sensor.The peak tension of the front shoelace was greater than that of the front and middle when the shoelace was loose and tight.The rear shoelace had the highest tension force.The study also found that shoelace tension varied throughout the gait cycle during running.Overall,this research provides a novel and validated method for measuring shoelace tensile stress,which has implications for developing automatic shoelace fastening systems.
基金supported by Sichuan Science and Technology Program(Grant No.2020YFH0080)the National Natural Science Foundation of China(Grant No.51475386)the National Basic Research Project of China(973 Program,Grant No.2015CB654801).
文摘The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.
基金supported by a National Health and Medical Research Council(NHMRC)Investigator Grant Emerging Leadership Level 1(Grant No.2017012).
文摘Purpose We aimed to investigate the effects of running shoe longitudinal bending stiffness(LBS)and midsole energy return on running economy and ankle mechanics and energetics.Methods PubMed,Scopus,SPORTDiscus,Embase,CINAHL,and Web of Science were systematically searched for this meta-analysis.Crossover studies comparing the effects of running shoe LBS and/or midsole energy return on at least 1 of the following outcomes:running economy,ankle plantarflexion moment,work,power,or angular velocity were included.Results Of the 2453 studies screened,48 were included(n=878).Results indicated that advanced footwear technologies(AFTs)significantly reduced oxygen consumption(standardized mean difference=–0.44,95%confidence interval:–0.60 to–0.28),p<0.001)as well as peak ankle moments and positive/negative ankle work and power.However,neither LBS nor midsole energy return alone significantly affected oxygen consumption,ankle moments,positive and negative work,or positive power.The effects of AFTs were moderated by the training status and speed of the runner.The quality of evidence for all outcomes were low or very low for all outcomes except the effect of LBS on negative ankle work.Conclusion AFT may improve running economy by minimizing ankle moments,work,and power.The absence of significant independent effects of LBS and midsole energy return suggests that the benefits of AFTs arise from the interaction of these properties.Further research is necessary to understand the mechanisms for improved running performance in AFTs.
文摘The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by 2024.However,the aforementioned goal is challenged by households that are scattered in remote areas.So far,Solar Home Systems(SHS)have mostly been applied to increase electricity access in rural areas.SHSs have continuous constraints to meet electricity demands and cannot run income-generating activities.The current research presents the feasibility study of electrifying Remera village with the smart microgrid as a case study.The renewable energy resources available in Remera are the key sources of electricity in that village.The generation capacity is estimated based on the load profile.The microgrid configurations are simulated with HOMER,and the genetic algorithm is used to analyze the optimum cost.By analyzing the impact of operation and maintenance costs,the results show that the absence of subsidies increases the levelized cost of electricity(COE)five times greater than the electricity price from the public utility.The microgrid made up of PV,diesel generator,and batteries proved to be the most viable solution and ensured continuous power supply to customers.By considering the subsidies,COE reaches 0.186$/kWh,a competitive price with electricity from public utilities in Rwanda.
基金Project(2023YFB4302500)supported by the National Key R&D Program of ChinaProject(52078485)supported by the National Natural Science Foundation of ChinaProjects(2021-Major-16,2021-Special-08)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.
基金supported by the NIH (R01NS103481, R01NS111776, and R01NS131489)Indiana Department of Health (ISDH58180)(all to WW)。
文摘Spinal cord injury necessitates effective rehabilitation strategies, with exercise therapies showing promise in promoting recovery. This study investigated the impact of rehabilitation exercise on functional recovery and morphological changes following thoracic contusive spinal cord injury. After a 7-day recovery period after spinal cord injury, mice were assigned to either a trained group(10 weeks of voluntary running wheel or forced treadmill exercise) or an untrained group. Bi-weekly assessments revealed that the exercise-trained group, particularly the voluntary wheel exercise subgroup, displayed significantly improved locomotor recovery, more plasticity of dopaminergic and serotonin modulation compared with the untrained group. Additionally, exercise interventions led to gait pattern restoration and enhanced transcranial magnetic motor-evoked potentials. Despite consistent injury areas across groups, exercise training promoted terminal innervation of descending axons. In summary, voluntary wheel exercise shows promise for enhancing outcomes after thoracic contusive spinal cord injury, emphasizing the role of exercise modality in promoting recovery and morphological changes in spinal cord injuries. Our findings will influence future strategies for rehabilitation exercises, restoring functional movement after spinal cord injury.
基金National Natural Science Foundation of China,No.42171455The Hong Kong RGC Research Impact Fund,No.R5011-23The Hong Kong General Research Fund,No.15204121。
文摘Urban environments offer a wealth of opportunities for residents to respite from their hectic life.Outdoor running or jogging becomes increasingly popular of an option.Impacts of urban environments on outdoor running,despite some initial studies,remain underexplored.This study aims to establish an analytical framework that can holistically assess the urban environment on the healthy vitality of running.The proposed framework is applied to two modern Chinese cities,i.e.,Guangzhou and Shenzhen.We construct three interpretable random forest models to explore the non-linear relationship between environmental variables and running intensity(RI)through analyzing the runners'trajectories and integrating with multi-source urban big data(e.g.,street view imagery,remote sensing,and socio-economic data)across the built,natural,and social dimensions,The findings uncover that road density has the greatest impact on RI,and social variables(e.g.,population density and housing price)and natural variables(e.g.,slope and humidity)all make notable impact on outdoor running.Despite these findings,the impact of environmental variables likely change across different regions due to disparate regional construction and micro-environments,and those specific impacts as well as optimal thresholds also alter.Therefore,construction of healthy cities should take the whole urban environment into account and adapt to local conditions.This study provides a comprehensive evaluation on the influencing variables of healthy vitality and guides sustainable urban planning for creating running-friendly cities.
文摘Objective:Running-related musculoskeletal injuries(RRMIs),especially stemming from overuse,frequently occur in runners.This study aimed to systematically review the literature and determine the incidence and prevalence proportion of RRMIs by anatomic location and specific pathology.Methods:An electronic database search with no date beginning restrictions was performed in SPORTDiscus,PubMed,and MEDLINE up to June 2020.Prospective studies were used to find the anatomic location and the incidence proportion of each RRMI,whereas retrospective or cross-sectional studies were used to find the prevalence proportion of each RRMI.A separate analysis for ultramarathon runners was performed.Results:The overall injury incidence and prevalence were 40.2%±18.8%and 44.6%±18.4%(mean±SD),respectively.The knee,ankle,and lower leg accounted for the highest proportion of injury incidence,whereas the knee,lower leg,and foot/toes had the highest proportion of injury prevalence.Achilles tendinopathy(10.3%),medial tibial stress syndrome(9.4%),patellofemoral pain syndrome(6.3%),plantar fasciitis(6.1%),and ankle sprains(5.8%)accounted for the highest proportion of injury incidence,whereas patellofemoral pain syndrome(16.7%),medial tibial stress syndrome(9.1%),plantar fasciitis(7.9%),iliotibial band syndrome(7.9%),and Achilles tendinopathy(6.6%)had the highest proportion of injury prevalence.The ankle(34.5%),knee(28.1%),and lower leg(12.9%)were the 3 most frequently injured sites among ultramarathoners.Conclusion:The injury incidence proportions by anatomic location between ultramarathoners and non-ultramarathoners were not significantly different(p=0.798).The pathologies with the highest incidence proportion of injuries were anterior compartment tendinopathy(19.4%),patellofemoral pain syndrome(15.8%),and Achilles tendinopathy(13.7%).The interpretation of epidemiological data in RRMIs is limited due to several methodological issues encountered.
文摘Dynamic running law of the hydraulic driving system decides the hoisting cage velocity curve in a hoisting cycle and is decided by the characteristic of the hydraulic driving system and by the operating speed of hoist driver. The paper studies the dynamic running law of hydraulic driving system, analyses the influence of driver operating speed on the dynamic running characteristic, and points out the reasonable driver operating speed to control the dynamic stress in rope and to reduce the oscillation of rope system.
基金Supported by the National Hi-tech Research and Development Program of China(2007AA04Z415)the Hunan Province and Xiangtan City Natural Science Joint Foundation(09JJ8005)the Torch Program Project of Hunan Province(2008SH044)
文摘An integrated monitoring system for running parameters of key mining equipmenton the basis of condition monitoring technology and modern communication networktechnology was developed.The system consists of a client computer with functions ofsignal acquisition and processing, and a host computer in the central control room.Thesignal acquisition module of the client computer can collect the running parameters fromvarious monitoring terminals in real-time.The DSP high-speed data processing system ofthe main control module can quickly achieve the numerical calculation for the collectedsignal.The signal modulation and signal demodulation are completed by the frequencyshift keying circuit and phase-locked loop frequency circuit, respectively.Finally, the signalis sent to the host computer for logic estimation and diagnostic analysis using the networkcommunication technology, which is helpful for technicians and managers to control therunning state of equipment.
基金provided by the National Natural Science Foundation of China(Grants No.12272238 and No.11932013)the"Outstanding Young Scholar"Program of Shanghai Municipalthe"Dawn"Program of Shanghai Education Commission(Grant No.19SG47)。
文摘Background:Foot kinematics,such as excessive eversion and malalignment of the hindfoot,are believed to be associated with running-related injuries.The maj ority of studies to date show that different foot strike patterns influence these specific foot and ankle kinematics.However,technical deficiencies in traditional motion capture approaches limit knowledge of in vivo joint kinematics with respect to rearfoot and forefoot strike patterns(RFS and FFS,respectively).This study uses a high-speed dual fluoroscopic imaging system(DFIS)to determine the effects of different foot strike patterns on 3D in vivo tibiotalar and subtalar joints kinematics.Methods:Fifteen healthy male recreational runners underwent foot computed tomography scanning for the construction of 3-dimensional models.A high-speed DFIS(100 Hz)was used to collect 6 degrees of freedom kinematics for participants’tibiotalar and subtalar joints when they adopted RFS and FFS in barefoot condition.Results:Compared with RFS,FFS exhibited greater internal rotation at 0%-20%of the stance phase in the tibiotalar joint.The peak internal rotation angle of the tibiotalar joint under FFS was greater than under RFS(p<0.001,Cohen’s d=0.92).RFS showed more dorsiflexion at 0%-20%of the stance phase in the tibiotalar joint than FFS.RFS also presented a larger anterior translation(p<0.001,Cohen’s d=1.28)in the subtalar joint at i nitial contact than FFS.Conclusion:Running with acute barefoot FFS increases the internal rotation of the tibiotalar joint in the early stance.The use of high-speed DFIS to quantify the movement of the tibiotalar and subtalar joint was critical to revealing the effects of RF S and FFS during running.
基金sponsored by National Natural Science Foundation of China (81800703 and 81970701)Beijing Nova Program (Z201100006820117 and 20220484181)+7 种基金Beijing Municipal Natural Science Foundation (7184252 and 7214258)the Fundamental Research Funds for the Central Universitiesthe Fundamental Research Funds for the Central Universities (BMU2021MX013)Peking University Clinical Scientist Training Program (BMU2023PYJH022)China Endocrine and Metabolism Young Scientific Talent Research Project (2022-N-02-01)Peking University Medicine Seed Fund for Interdisciplinary ResearchChina Diabetes Young Scientific Talent Research ProjectBethune-Merck Diabetes Research Fund of Bethune Charitable Foundation (G2018030)。
文摘Exercise training is critical for the early prevention and treatment of obesity and diabetes mellitus.However,the mechanism with gut microbiota and fecal metabolites underlying the effects of voluntary wheel running on high-fat diet induced abnormal glucose metabolism has not been fully elaborated.C57BL/6 male mice were randomly assigned to 4 groups according to diets(fed with normal chow diet or high-fat diet)and running paradigm(housed in static cage or with voluntary running wheel).An integrative 16S rDNA sequencing and metabolites profiling was synchronously performed to characterize the effects of voluntary wheel running on gut microbiota and metabolites.It showed that voluntary wheel running prevented the detrimental effects of high-fat feeding on glucose metabolism 16S rDNA sequencing showed remarkable changes in Rikenella and Marvinbryantia genera.Metabolic profiling indicated multiple altered metabolites,which were enriched in secondary bile acid biosynthesis signaling.In conclusion,our study indicated that voluntary wheel running significantly improved glucose metabolism and counteracted the deleterious effects of high-fat feeding on body weight and glucose intolerance.We further found that voluntary wheel running could integratively program gut microbiota composition and fecal metabolites changes,and may regulate muricholic acid metabolism and secondary bile acid biosynthesis in high-fat fed mice.
基金Projects(52022113,52278546)supported by the National Natural Science Foundation of ChinaProject(2020EEEVL0403)supported by the China Earthquake Administration。
文摘Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.
基金The authors would like to acknowledge Jordyn Vienneau,Aimee(Smith)Mears,Christian Meyer,and Antonio Blago for their support in collecting data for this study.The authors would like to thank Adidas(Herzogenaurach,Germany)for providing the test shoes.
文摘Purpose This study aimed to investigate whether there is a systematic change of leg muscle activity,as quantified by surface electromyography(EMG),throughout a standard running footwear assessment protocol at a predetermined running speed.Methods Thirty-one physically active adults(15 females and 16 males)completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s.The level of muscle activity from 6 major leg muscles was recorded using surface EMG.The variables assessed were the EMG total intensity as a function of time and the cumulative EMG overall intensity.Systematic effects of the chronological testing round(independent variable)on the normalized EMG overall intensity(dependent variable)were examined using Friedman analysis of variates and post hoc pairwise Wilcoxon signed-rank tests(α=0.05).Results There was a systematic reduction in overall EMG intensity for all 6 muscles over the time course of the running protocol(p<0.001)until the fourth testing round when EMG intensities reached a steady state.The one exception was the biceps femoris muscle,which showed a significant reduction of EMG intensity during the stance phase(p<0.001)but not the swing phase(p=0.16).Conclusion While running at a predetermined speed,the neuromuscular system undergoes an adaptation process characterized by a progressive reduction in the activity level of major leg muscles.This process may represent an optimization strategy of the neuromuscular system towards a more energetically efficient running style.Future running protocols should include a familiarization period of at least 7 min or 600 strides of running at the predetermined speed.
文摘Helicopter blade running elevation measurement is an important measure target in helicopter blade dynamic balance experimentation. The elevation influences the helicopter＇ s security and other performance capabilities. In testing, however, it has been difficult to measure the elevation when the rotor reaches high speeds. To get a simple, fast and highly accurate measurement system, photo electricity technology was applied to measuring the blade running elevation. Discussed is the measurement principle of blade running elevation, tire design of the measurement system and analysis of the measurement precision.
文摘Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a pandemic.The use of face masks and respirators is an important public health measure to reduce or prevent transmission of SARS-CoV-2.Here we discuss the hypothetical mechanisms by which exercise with face masks or respirators can induce detrimental effects on the cardiovascular system,potentially explaining adverse events such as cardiac arrhythmias and spontaneous pneumothorax.Although sudden death associated with the wearing of a face mask during running is a rare event,the risk is higher especially in those with existing cardiac comorbidities.In such cases,a mask designed specifi cally for runners with no or few side effects of oxygen defi ciency should be considered instead.
基金supported by the National Key R&D Program“Transportation Infrastructure”“Reveal The List and Take Command”project(2022YFB2603301)National Natural Science Foundation of China(No.52078498)+3 种基金Natural Science Foundation of Hunan Province of China(No.2022JJ30745)Frontier cross research project of Central South University(No.2023QYJC006)Hunan Provincial Science and Technology Promotion Talent Project(No.2020TJ-Q19)Science and Technology Research and Development Program Project of China railway group limited(Major Special Project,No.2021-Special-04-2)。
文摘The accurate assessment of running safety during earthquakes is of significant importance for ensuring the safety of railway lines.Currently,assessment methods based on a single index suffer from issues such as misjudgment of operational safety and difficulty in evaluating operational margin,making them unsuitable for assessing train safety during earthquakes.Therefore,in order to propose an effective evaluation method for the running safety of trains during earthquakes,this study employs three indexes,namely lateral displacement of the wheel–rail contact point,wheel unloading rate,and wheel lift,to describe the lateral and vertical contact states between the wheel and rail.The corresponding evolution characteristics of the wheel–rail contact states are determined,and the derailment forms under different frequency components of seismic motion are identified through dynamic numerical simulations of the train–track coupled system under sine excitation.The variations in the wheel–rail contact states during the transition from a safe state to the critical state of derailment are analyzed,thereby constructing the evolutionary path of train derailment and seismic derailment risk domain.Lastly,the wheel–rail contact and derailment states under seismic conditions are analyzed,thus verifying the effectiveness of the evaluation method for assessing running safety under earthquakes proposed in this study.The results indicate that the assessment method based on the derailment risk domain accurately and comprehensively reflects the wheel–rail contact states under seismic conditions.It successfully determines the forms of train derailment,the risk levels of derailment,and the evolutionary paths of derailment risk.
基金supported by the Research Major Project of China Academy of Railway Sciences Group Co.,Ltd(Grant No.2021YJ270)the China National Railway Group Science and Technology Program(Grant No.N2022T001).
文摘Purpose-Express freight transportation is in rapid development currently.Owing to the higher speed of express freight train,the deformation of the bridge deck worsens the railway line condition under the action of wind and train moving load when the train runs over a long-span bridge.Besides,the blunt car body of vehicle has poor aerodynamic characteristics,bringing a greater challenge on the running stability in the crosswind.Design/methodology/approach-In this study,the aerodynamic force coefficients of express freight vehicles on the bridge are measured by scale model wind tunnel test.The dynamic model of the train-long-span steel truss bridge coupling system is established,and the dynamic response as well as the running safety of vehicle are evaluated.Findings-The results show that wind speed has a significant influence on running safety,which is mainly reflected in the over-limitation of wheel unloading rate.The wind speed limit decreases with train speed,and it reduces to 18.83 m/s when the train speed is 160 km/h.Originality/value-This study deepens the theoretical understanding of the interaction between vehicles and bridges and proposes new methods for analyzing similar engineering problems.It also provides a new theoretical basis for the safety assessment of express freight trains.
文摘In order to convey complete meanings,there is a phenomenon in Chinese of using multiple running sentences.Xu Jingning(2023,p.66)states,“In communication,a complete expression of meaning often requires more than one clause,which is common in human languages.”Domestic research on running sentences includes discussions on defining the concept and structural features of running sentences,sentence properties,sentence pattern classifications and their criteria,as well as issues related to translating running sentences into English.This article primarily focuses on scholarly research into the English translation of running sentences in China,highlighting recent achievements and identifying existing issues in the study of running sentence translation.However,by reviewing literature on the translation of running sentences,it is found that current research in the academic community on non-core running sentences is limited.Therefore,this paper proposes relevant strategies to address this issue.
基金The National Key Technology R&D Program of China during the 11th Five-Year Plan Period(No.2006BAH02A06)
文摘A real-life milk run system designing problem of an engine manufacturer adopted JIT(just-in-time)production is studied.In the process of milk run system planning and design,the supply base is identified and a supplier site map is plotted for an arrangement of routes on which parts are periodically collected in a JIT manner from many scattered suppliers.With unit load designing,vehicle choosing and fleet sizing,pickup routing,vehicle assigning and scheduling problems are studied.Among these problems,a CVRP problem is identified and formulated as the key optimization in designing this milk run system,and it is solved through an optimization process.This tactical planning and optimization process gives a good solution to the real problem,and may shed light on the planning of similar systems.
