Physiological performance in lizards may be affected by climate across latitudinal or altitudinal gradients.In the coastal dune barriers in central-eastern Argentina,the annual maximum environmental temperature decrea...Physiological performance in lizards may be affected by climate across latitudinal or altitudinal gradients.In the coastal dune barriers in central-eastern Argentina,the annual maximum environmental temperature decreases up to 2℃ from low to high latitudes,while the mean relative humidity of the air decreases from 50%to 25%.Liolaemus multimaculatus,a lizard in the family Liolaemidae,is restricted to these coastal dunes.We investigated the locomotor performance of the species at 6 different sites distributed throughout its range in these dune barriers.We inquired whether locomotor performance metrics were sensitive to the thermal regime attributable to latitude.The thermal performance breadth increased from 7%to 82%with latitude,due to a decrease in its critical thermal minimum of up to 5℃ at higher latitudes.Lizards from high latitude sites showed a thermal optimum,that is,the body temperature at which maximum speed is achieved,up to 4℃lower than that of lizards from the low latitude.At relatively low temperatures,the maximum running speed of high-latitude individuals was faster than that of low-latitude ones.Thermal parameters of locomotor performance were labile,decreasing as a function of latitude.These results show populations of L.multimaculatus adjust thermal physiology to cope with local climatic variations.This suggests that thermal sensitivity responds to the magnitude of latitudinal fluctuations in environmental temperature.展开更多
In this paper we investigated how the running speed would affect the dynamics of body pitching,and whether body inertiais important for animals.Passive trotting of spring-mass model and passive bounding of spring-beam...In this paper we investigated how the running speed would affect the dynamics of body pitching,and whether body inertiais important for animals.Passive trotting of spring-mass model and passive bounding of spring-beam model were studied atdifferent speeds for different sets of body parameters respectively.Furthermore,different body inertias were used in bounding.We found that running speed exerts effect on leg performance by means of centrifugal force.The centrifugal force can be understoodas an enhancement to the natural frequency of the spring-mass system.The disadvantage of body pitching may beoffset by the great increase in centrifugal force at high speed.The results also reveal that body mass distribution might not be themain reason for the difference in maximal running speeds of different animals.展开更多
The consistency of the dynamic behavior of the mechanical equivalent model of high-speed pantographs with that of actual high-speed pantographs under service conditions is crucial for the correctness and accuracy of t...The consistency of the dynamic behavior of the mechanical equivalent model of high-speed pantographs with that of actual high-speed pantographs under service conditions is crucial for the correctness and accuracy of the numerical simulation results of the pantograph-catenary interaction.Firstly,based on experimental data and the finite element method,models of a mass-point frame and reduced pan head were established,which can simulate the rolling and pitching motion characteristics of the dual-strip pan head.The correctness of the finite element numerical simulation of the pantograph-catenary system based on the model was verified through an industry standard and line tests.Then,the variation law of the standard deviation of the contact force(SDCF)in the speed range of 240-450 km/h was studied,and the mechanism of large fluctuation in SDCF was explained from the perspective of pantograph-catenary resonance.Finally,the influence of pan head degree of freedom and low-pass filtering frequency of the contact force time-domain signal on SDCF was studied,and the applicable speed level of the traditional three-mass model and 20 Hz filtering were provided.展开更多
A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction c...A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction cylinder and the running speed of the hydraulic cylinder.In the experiment the concentrations of coal slime were 75.7%,76.3%,74.4%,73.5%,72.1%and 70.63%;the running speeds were 0.23,0.18,0.13,0.10 and 0.08 m/s;and the slenderness ratios of the suction cylinder were 1.63,2.26,2.88,3.50,4.13,4.78 and 5.38.The results show that the suction volumetric efficiency decreases gradually with an increase in material concentration.The critical concentration value is 72%;below 72%the suction volumetric efficiency is above 90%,otherwise it decreases rapidly.When the solid concentration reaches 76.3%,the suction volumetric efficiency is only 40%.When the running speed of the piston is less than or equal to 0.23 m/s,the suction volumetric efficiency increases with an increase in running speed.展开更多
The maximum locomotor capabilities of theropod dinosaurs have long been a subject of considerable scholarly,primarily due to the lack of contemporary species for direct comparison.Biomechanical modeling and the analys...The maximum locomotor capabilities of theropod dinosaurs have long been a subject of considerable scholarly,primarily due to the lack of contemporary species for direct comparison.Biomechanical modeling and the analysis of dinosaur trackways have yielded significant theoretical insights into this area of research.This study investigates the running speed of a mid-sized theropod dinosaur trackway recently identified in the Otog region of Inner Mongolia,and it juxtaposes these findings with other running theropod trackways from diverse various global locations utilizing standardized inference methodologies.The results indicate that the trackmaker was capable of achieving a running speed of 45 or 41±4.9 km/h,thereby establishing it as the fastest-running theropod trackway documented from the Cretaceous period.Additionally,this paper reviews biomechanical investigations concerning the maximum running speeds of theropod dinosaurs and illustrates that the inferred speed of this midsized theropod aligns with the predictions of the majority of biomechanical models,thereby providing compelling new evidence to enhance our understanding of the locomotor capabilities of mid-sized theropods.展开更多
In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performa...In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performance that may affectfitness.Scorpions of the genus Ananteris autotomize the“tail”,which in fact corresponds to the last abdominal segments.After autotomy,individuals lose nearly 25%of their body mass and the last portion of the digestive tract,including the anus,which prevents defecation and leads to constipation,because regeneration does not occur.Here,we experimentally investigated the short-and long-term effects of tail loss on the locomotor performance of Ananteris balzani.In a short-term experiment,the maximum running speed(MRS)of males and females did not change after autotomy.Moreover,the relative mass of the lost tail did not affect the change in MRS after autotomy.In a long-term experiment,autotomy had a negative effect on the MRS of males,but not of females.Autotomized over-fed individuals suffered from severe constipation but were not slower than autotomized normally fed individuals.In conclusion,tail loss has no immediate effect on the locomotor performance of scorpions.The long-term decrease in the locomotor performance of autotomized males may impair mate searching.However,because death by constipation takes several months,males have a long time tofind mates and reproduce.Thus,the prolonged period between autotomy and death by constipation is crucial for understanding the evolution of one of the most extreme cases of autotomy in nature.展开更多
基金This work was supported by the ANPCYT-FONCYT[PICT 2016-0677]the UNMdP[15E/695,EXA 745/15].
文摘Physiological performance in lizards may be affected by climate across latitudinal or altitudinal gradients.In the coastal dune barriers in central-eastern Argentina,the annual maximum environmental temperature decreases up to 2℃ from low to high latitudes,while the mean relative humidity of the air decreases from 50%to 25%.Liolaemus multimaculatus,a lizard in the family Liolaemidae,is restricted to these coastal dunes.We investigated the locomotor performance of the species at 6 different sites distributed throughout its range in these dune barriers.We inquired whether locomotor performance metrics were sensitive to the thermal regime attributable to latitude.The thermal performance breadth increased from 7%to 82%with latitude,due to a decrease in its critical thermal minimum of up to 5℃ at higher latitudes.Lizards from high latitude sites showed a thermal optimum,that is,the body temperature at which maximum speed is achieved,up to 4℃lower than that of lizards from the low latitude.At relatively low temperatures,the maximum running speed of high-latitude individuals was faster than that of low-latitude ones.Thermal parameters of locomotor performance were labile,decreasing as a function of latitude.These results show populations of L.multimaculatus adjust thermal physiology to cope with local climatic variations.This suggests that thermal sensitivity responds to the magnitude of latitudinal fluctuations in environmental temperature.
文摘In this paper we investigated how the running speed would affect the dynamics of body pitching,and whether body inertiais important for animals.Passive trotting of spring-mass model and passive bounding of spring-beam model were studied atdifferent speeds for different sets of body parameters respectively.Furthermore,different body inertias were used in bounding.We found that running speed exerts effect on leg performance by means of centrifugal force.The centrifugal force can be understoodas an enhancement to the natural frequency of the spring-mass system.The disadvantage of body pitching may beoffset by the great increase in centrifugal force at high speed.The results also reveal that body mass distribution might not be themain reason for the difference in maximal running speeds of different animals.
基金supported by the Major Project of China Railway Co.,Ltd.(Grant No.K2021J004-A)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB22020201)。
文摘The consistency of the dynamic behavior of the mechanical equivalent model of high-speed pantographs with that of actual high-speed pantographs under service conditions is crucial for the correctness and accuracy of the numerical simulation results of the pantograph-catenary interaction.Firstly,based on experimental data and the finite element method,models of a mass-point frame and reduced pan head were established,which can simulate the rolling and pitching motion characteristics of the dual-strip pan head.The correctness of the finite element numerical simulation of the pantograph-catenary system based on the model was verified through an industry standard and line tests.Then,the variation law of the standard deviation of the contact force(SDCF)in the speed range of 240-450 km/h was studied,and the mechanism of large fluctuation in SDCF was explained from the perspective of pantograph-catenary resonance.Finally,the influence of pan head degree of freedom and low-pass filtering frequency of the contact force time-domain signal on SDCF was studied,and the applicable speed level of the traditional three-mass model and 20 Hz filtering were provided.
基金Projects 02C26211100499 supported by Science and Technology Corporation Innovation Fund of China 20020290011 by the Ph.D Program Fund
文摘A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction cylinder and the running speed of the hydraulic cylinder.In the experiment the concentrations of coal slime were 75.7%,76.3%,74.4%,73.5%,72.1%and 70.63%;the running speeds were 0.23,0.18,0.13,0.10 and 0.08 m/s;and the slenderness ratios of the suction cylinder were 1.63,2.26,2.88,3.50,4.13,4.78 and 5.38.The results show that the suction volumetric efficiency decreases gradually with an increase in material concentration.The critical concentration value is 72%;below 72%the suction volumetric efficiency is above 90%,otherwise it decreases rapidly.When the solid concentration reaches 76.3%,the suction volumetric efficiency is only 40%.When the running speed of the piston is less than or equal to 0.23 m/s,the suction volumetric efficiency increases with an increase in running speed.
基金supported by the National Natural Science Foundation of China(Grant No.42288201)the Education Department of Liaoning Province(Grant No.JYTQN2023424)+1 种基金the Fundamental Research Funds for the Liaoning Universities(Grant No.LJ202410166028)the Otog Local Cooperation Project Funding。
文摘The maximum locomotor capabilities of theropod dinosaurs have long been a subject of considerable scholarly,primarily due to the lack of contemporary species for direct comparison.Biomechanical modeling and the analysis of dinosaur trackways have yielded significant theoretical insights into this area of research.This study investigates the running speed of a mid-sized theropod dinosaur trackway recently identified in the Otog region of Inner Mongolia,and it juxtaposes these findings with other running theropod trackways from diverse various global locations utilizing standardized inference methodologies.The results indicate that the trackmaker was capable of achieving a running speed of 45 or 41±4.9 km/h,thereby establishing it as the fastest-running theropod trackway documented from the Cretaceous period.Additionally,this paper reviews biomechanical investigations concerning the maximum running speeds of theropod dinosaurs and illustrates that the inferred speed of this midsized theropod aligns with the predictions of the majority of biomechanical models,thereby providing compelling new evidence to enhance our understanding of the locomotor capabilities of mid-sized theropods.
基金supported by grants of the Fundação de AmparoàPesquisa do Estado de São Paulo(2015/10448-4 to GM,2017/05283-1 to SGH)Conselho Nacional de Desenvolvimento Científico e Tecnológico(306550/2014-8 to GM).
文摘In many taxa,individuals voluntarily detach a body part as a form to increase their chances of escaping predation.This defense mechanism,known as autotomy,has several consequences,such as changes in locomotor performance that may affectfitness.Scorpions of the genus Ananteris autotomize the“tail”,which in fact corresponds to the last abdominal segments.After autotomy,individuals lose nearly 25%of their body mass and the last portion of the digestive tract,including the anus,which prevents defecation and leads to constipation,because regeneration does not occur.Here,we experimentally investigated the short-and long-term effects of tail loss on the locomotor performance of Ananteris balzani.In a short-term experiment,the maximum running speed(MRS)of males and females did not change after autotomy.Moreover,the relative mass of the lost tail did not affect the change in MRS after autotomy.In a long-term experiment,autotomy had a negative effect on the MRS of males,but not of females.Autotomized over-fed individuals suffered from severe constipation but were not slower than autotomized normally fed individuals.In conclusion,tail loss has no immediate effect on the locomotor performance of scorpions.The long-term decrease in the locomotor performance of autotomized males may impair mate searching.However,because death by constipation takes several months,males have a long time tofind mates and reproduce.Thus,the prolonged period between autotomy and death by constipation is crucial for understanding the evolution of one of the most extreme cases of autotomy in nature.
