A novel refined dynamic model of high-speed maglev train-bridge coupled system for random vibration and running safety assessment

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.

SmartMicro Grid Energy System Management Based on Optimum Running Cost for Rural Communities in Rwanda

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.

Enhancement of motor functional recovery in thoracic spinal cord injury: voluntary wheel running versus forced treadmill exercise

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.

Voluntary wheel running ameliorated the deleterious effects of high-fat diet on glucose metabolism,gut microbiota and microbial-associated metabolites

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.

Influence of pier height on the safety of trains running on high-speed railway bridges during earthquakes

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.

Acute effect of foot strike patterns on in vivo tibiotalar and subtalar joint kinematics during barefoot running

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.

Running safety assessment method of trains under seismic conditions based on the derailment risk domain

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.

Safety of the express freight train running over a long-span bridge

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.

Review of Research on English Translation of Chinese Running Sentences

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.

A systematic review of running-related musculoskeletal injuries in runners

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.

The integrated monitoring system for running parameters of key mining equipment based on condition monitoring technology

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.

Systematic reduction of leg muscle activity throughout a standard assessment of running footwear

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.

Study of the helicopter blade running elevation measurement system

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.

Running with Face Masks or Respirators Can Be Detrimental to the Respiratory and Cardiovascular Systems

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.

The dynamic running law study on driving system of hydraulic winder

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.

Free running period affected by network structures of suprachiasmatic nucleus neurons exposed to constant light

Exposed to the natural light-dark cycle,24 h rhythms exist in behavioral and physiological processes of living beings.Interestingly,under constant darkness or constant light,living beings can maintain a robust endogenous rhythm with a free running period(FRP)close to 24 h.In mammals,the circadian rhythm is coordinated by a master clock located in the suprachiasmatic nucleus(SCN)of the brain,which is composed of about twenty thousand self-oscillating neurons.These SCN neurons form a heterogenous network to output a robust rhythm.Thus far,the exact network topology of the SCN neurons is unknown.In this article,we examine the effect of the SCN network structure on the FRP when exposed to constant light by a Poincare model.Four typical network structures are considered,including a nearest-neighbor coupled network,a Newman-Watts small world network,an Erd¨os-Renyi random network and a Barabasi-Albert(BA)scale free network.The results show that the FRP is longest in the BA network,because the BA network is characterized by the most heterogeneous structure among these four types of networks.These findings are not affected by the average node degree of the SCN network or the value of relaxation rate of the SCN neuronal oscillators.Our findings contribute to the understanding of how the network structure of the SCN neurons influences the FRP.

Pile Running in Layered Soils

This paper presents a case study on incidents of offshore pile running in layered soils.The study provides a detailed description of the seabed soil data,pile driving records,and field surveillance video observations.Three-dimensional large deformation finite element(LDFE)analyses were conducted to retrospectively analyze the incidents,considering the remoulding of seabed soil and degradation of the pile-soil interface in the LDFE modeling.By comparing the field observations with the LDFE analysis,the mechanism of pile running was discussed,with a focus on investigating the pile penetration resistance in each layer.The study revealed that pile running in layered soils primarily resulted from a significant reduction in pile base resistance when transitioning from a strong layer to an adjacent weak layer.To further investigate the pile running mechanism in layered soils,a parametric study on the strength variation of adjacent soil layers and its influence on pile base resistance was conducted.Lastly,a simplified prediction model of pile base resistance,suitable for assessing the risk of pile running in layered soils,was proposed.

Does orthotics use improve comfort,speed,and injury rate during running?A randomised control trial

BACKGROUND Running is a hugely popular sport.Unfortunately,running-related injury(RRI)rates are high,particularly amongst amateur and recreational runners.Finding ways to reduce RRI rates and maximise comfort and performance for runners is important.Evidence regarding whether orthotics can successfully improve these parameters is limited and contradicting.Further research is required to provide runners with clearer guidance on the usefulness of orthotics.AIM To investigate the effect of Aetrex Orthotics on comfort,speed and RRI rates during recreational running.METHODS One hundred and six recreational runners were recruited on a voluntary basis via running clubs and social media pages and randomised into either the intervention or control group.Participants in the intervention group ran with Aetrex L700 Speed Orthotics inserted in their usual running shoes,whilst participants in the control group ran in their usual running shoes with no orthotics.The study ran for an 8-wk period.Participants provided data relating to running comfort,distance,and time during weeks 3-6.Participants provided data relating to any RRIs they sustained during all 8 wks.Running distance and time were used to calculate running speed in miles per hour(mph).For each outcome variable,95%confidence intervals and P values were calculated to assess the statistical significance between the groups.For comfort and speed data,univariate multi-level analysis was performed,and for outcome variables with significant between group differences,multi-level multivariate analysis was performed to evaluate any confounding effects of gender and age.RESULTS Ninety-four participants were included in the final analysis(drop-out rate=11%).Comfort and speed from 940 runs and 978 injury data reports were analysed.Participants who ran with orthotics reported,on average,speeds 0.30 mph faster(P=0.20)and comfort scores 1.27 points higher(P≤0.001)than participants who ran with no orthotics.They were also 2.22 times less likely to sustain an injury(P=0.08)than participants who ran with no orthotics.However,findings were only significant for comfort and not for speed or injury rates.Age and gender were found to be significant predictors of comfort.However,the improvements in comfort reported by participants who ran with orthotics were still significant after adjusting for age and gender.CONCLUSION This study found orthotics to improve comfort and speed and prevent RRIs whilst running.However,these findings were only statistically significant for comfort.

Tactical planning and optimization of a milk run system of parts pickup for an engine manufacturer

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.

Study on the Recycling Agricultural System Operation Mechanism Focusing on Pig Farming

According to the characteristics of circular agricultural mode focusing on pig farming and by dint of system dynamics mode-based analysis techniques to analyze the characteristics,the operation force for the recycling agricultural system focusing on pig farming was put forward.