Cleat serves as the primary flow pathway for coalbed methane(CBM)and water.However,few studies consider the impact of local contact on two-phase flow within cleats.A visual generalized model of endogenous cleats was c...Cleat serves as the primary flow pathway for coalbed methane(CBM)and water.However,few studies consider the impact of local contact on two-phase flow within cleats.A visual generalized model of endogenous cleats was constructed based on microfluidics.A microscopic and mesoscopic observation technique was proposed to simultaneously capture gas-liquid interface morphology of pores and throat and the two-phase flow characteristics in entire cleat system.The local contact characteristics of cleats reduced absolute permeability,which resulted in a sharp increase in the starting pressure.The reduced gas flow capacity narrowed the co-infiltration area and decreased water saturation at the isotonic point in a hydrophilic environment.The increased local contact area of cleats weakened gas phase flow capacity and narrowed the co-infiltration area.Jumping events occurred in methane-water flow due to altered porosity caused by local contact in cleats.The distribution of residual phases changed the jumping direction on the micro-scale as well as the dominant channel on the mesoscale.Besides,jumping events caused additional energy dissipation,which was ignored in traditional two-phase flow models.This might contribute to the overestimation of relative permeability.The work provides new methods and insights for investigating unsaturated flow in complex porous media.展开更多
In this study,we present a small,integrated jumping-crawling robot capable of intermittent jumping and self-resetting.Compared to robots with a single mode of locomotion,this multi-modal robot exhibits enhanced obstac...In this study,we present a small,integrated jumping-crawling robot capable of intermittent jumping and self-resetting.Compared to robots with a single mode of locomotion,this multi-modal robot exhibits enhanced obstacle-surmounting capabilities.To achieve this,the robot employs a novel combination of a jumping module and a crawling module.The jumping module features improved energy storage capacity and an active clutch.Within the constraints of structural robustness,the jumping module maximizes the explosive power of the linear spring by utilizing the mechanical advantage of a closed-loop mechanism and controls the energy flow of the jumping module through an active clutch mechanism.Furthermore,inspired by the limb movements of tortoises during crawling and self-righting,a single-degree-of-freedom spatial four-bar crawling mechanism was designed to enable crawling,steering,and resetting functions.To demonstrate its practicality,the integrated jumping-crawling robot was tested in a laboratory environment for functions such as jumping,crawling,self-resetting,and steering.Experimental results confirmed the feasibility of the proposed integrated jumping-crawling robot.展开更多
This paper is concerned with the reflected stochastic Burgers equation driven both by the Brownian motion and by the Poisson random measure.The existence and uniqueness of solutions are established.The penalization me...This paper is concerned with the reflected stochastic Burgers equation driven both by the Brownian motion and by the Poisson random measure.The existence and uniqueness of solutions are established.The penalization method plays an important role.展开更多
Bio-inspired jumping robots have emerged as a promising solution for traversing complex terrains inaccessible to conventional locomotion systems.Drawing upon the exceptional jumping kinematics observed in insects,rese...Bio-inspired jumping robots have emerged as a promising solution for traversing complex terrains inaccessible to conventional locomotion systems.Drawing upon the exceptional jumping kinematics observed in insects,researchers have developed multiple robotic prototypes mimicking biological propulsion mechanisms.However,the principal technological barrier resides in actuator systems,where current energy storage technologies suffer from inadequate energy density,fundamentally limiting takeoff velocity and jumping height.To overcome these limitations,we present a novel combustion-explosive propulsion system exhibiting high mass-specific energy release and rapid acceleration characteristics.By integrating this propulsion mechanism with a unique jumping leg structure,experimental validation through prototype testing demonstrated vertical leaps reaching 20 cm(1.67 times body length)under laboratory conditions,accompanied by comprehensive thermodynamic modeling using ABAQUS simulations that validated the effectiveness of this actuation system.The integrated design approach combines bionic structural design with combustible fuel formulations to offer new possibilities for the development of highly flexible robotic systems capable of negotiating obstacles in disaster response scenarios.展开更多
Jumping robots are highly capable of overcoming obstacles.However,their explosive force,short duration,and variable trajectories pose significant challenges in achieving stable landings in complex environments.Traditi...Jumping robots are highly capable of overcoming obstacles.However,their explosive force,short duration,and variable trajectories pose significant challenges in achieving stable landings in complex environments.Traditional approaches rely heavily on sophisticated algorithms and electronic sensor feedback systems to ensure landing stability,which increases the implementation complexity.Inspired by the process by which humans complete jumps and achieve stable landings in complex environments,this study proposes a novel landing control method for jumping robots.By designing a mechanically coupled perception-control structure based on mechanical logic computing,the robot simulates the real-time transmission of neural signals triggered by the ground reaction force(GRF)in human reflex loops,thereby simplifying traditional control approaches.Through the collaboration of a flexible mechanical spine and a bistable foot module,the robot achieves an average height of 16.8 cm and a distance of 25.36 cm in consecutive stable jumps.It also demonstrates reliable landing performance on challenging terrain including slopes and cobblestone surfaces.This paper proposes a novel landing control method for jumping robots that simplifies traditional control approaches.The method enables stable landings on complex terrain through a mechanically coupled perception-control structure.This approach has potential applications in tasks requiring mobility over uneven terrain,such as search and rescue.展开更多
ClO4)2 (MnCP),(ClO4)2 (NiCP) and (ClO4) 2 (PbCP) (CHZ=Carbohydrazide) were flash pyrolyzed at different temperatures und er the set pressure by T-jump/FTIR spectroscopy. The results show that twelve ga s products obta...ClO4)2 (MnCP),(ClO4)2 (NiCP) and (ClO4) 2 (PbCP) (CHZ=Carbohydrazide) were flash pyrolyzed at different temperatures und er the set pressure by T-jump/FTIR spectroscopy. The results show that twelve ga s products obtained during the flash pyrolysis process of the three complexes we re CO2, CO, HCl, HCN, NH3, NO2, N2O, NO, HNCO, HONO, H2C=O and H2O, of which CO2 , HCN and HCl were the main gas products and CO2 was the most novel product. NH3 was oxidized to NO2, N2O and H2O. At least some of the N2O might result from th is reaction. Additionally, the effect of temperature on the gas products is disc ussed and the concentration-time change curves of the main gas products are give n.展开更多
背景:肢体间不对称是人类生长发育过程中的一般现象,长期专项训练可使运动员肢体间不对称发生特异性适应。目的:回顾了体育运动中肢体间不对称的形成原因、表现形式及对运动能力的影响,并概述了相关评估方法及干预策略。方法:检索中国...背景:肢体间不对称是人类生长发育过程中的一般现象,长期专项训练可使运动员肢体间不对称发生特异性适应。目的:回顾了体育运动中肢体间不对称的形成原因、表现形式及对运动能力的影响,并概述了相关评估方法及干预策略。方法:检索中国知网、万方、PubMed及Web of Science数据库建库至2024年9月间收录的文献,中文检索词为“不对称,对称,失衡,平衡,力量,爆发力,跳跃,跑,人体测量学,运动损伤,运动能力,运动表现”,英文检索词为“asymmetry,asymmetries,asymmetric,asymmetrical,imbalance,strength,power,force,jump,sprint,athletic performance,anthropometry,injury”。排除重复发表、内容不相关及会议文献后,最终纳入131篇文献进行分析。结果与结论:(1)肢体间不对称可受遗传、任务、训练、损伤、疲劳和肢体偏好等因素影响,主要表现为解剖结构、力量表现、专项任务不对称等形式;(2)肢体间不对称增大可导致双侧同相位对称类运动能力受损,但与双侧异相位对称类运动能力间关系尚不明确;(3)训练干预可有效改善肢体间不对称,且单侧训练效果优于双侧,训练方式和内容选择应符合专项需求;(4)为进一步厘清肢体间不对称与运动能力间的关系,建议未来研究秉承肢体间不对称的“任务特异性”理念,规范研究设计,选择敏感测试手段与指标,统一计算方式以提供更多的高质量证据,并分类制定不同专项肢体间不对称的预警阈值标准。展开更多
Using conventional mathematical statistics,linear regression and the standard deviation,the quantitative analysis was made on the climate changes in Shenyang.The results showed that the trend of precipitation reduced ...Using conventional mathematical statistics,linear regression and the standard deviation,the quantitative analysis was made on the climate changes in Shenyang.The results showed that the trend of precipitation reduced 155 mm,which was made the greatest contribution by summer and autumn.It decreased 43 mm on the average after the climate jump.The precipitation variability in spring increased and drought risk in spring increased.The first soaking rain limited the spring planting time.The temperature trend raised 1.3℃,mainly in spring and winter.The frost-free period extended about 13 d.The accumulated temperature trends in crop growing season increased 290℃ and it had an average increase of 178℃ after the climate jump.This trend of climate warming made the end of last frost advanced.Early sowing of crops suitably was possible,which was beneficial for agricultural production.The precipitation decrease,the time delay and instability of the first soaking rain were unfavorable for crop growth and seeding.And they became the factors that constrained the normal growth and stabile yield raise of crops.展开更多
基金the financial support from the National Natural Science Foundation of China (No.42102127)the Postdoctoral Research Foundation of China (No.2024 M751860)。
文摘Cleat serves as the primary flow pathway for coalbed methane(CBM)and water.However,few studies consider the impact of local contact on two-phase flow within cleats.A visual generalized model of endogenous cleats was constructed based on microfluidics.A microscopic and mesoscopic observation technique was proposed to simultaneously capture gas-liquid interface morphology of pores and throat and the two-phase flow characteristics in entire cleat system.The local contact characteristics of cleats reduced absolute permeability,which resulted in a sharp increase in the starting pressure.The reduced gas flow capacity narrowed the co-infiltration area and decreased water saturation at the isotonic point in a hydrophilic environment.The increased local contact area of cleats weakened gas phase flow capacity and narrowed the co-infiltration area.Jumping events occurred in methane-water flow due to altered porosity caused by local contact in cleats.The distribution of residual phases changed the jumping direction on the micro-scale as well as the dominant channel on the mesoscale.Besides,jumping events caused additional energy dissipation,which was ignored in traditional two-phase flow models.This might contribute to the overestimation of relative permeability.The work provides new methods and insights for investigating unsaturated flow in complex porous media.
基金supported by the National Natural Science Foundation of China(Nos.51375383).
文摘In this study,we present a small,integrated jumping-crawling robot capable of intermittent jumping and self-resetting.Compared to robots with a single mode of locomotion,this multi-modal robot exhibits enhanced obstacle-surmounting capabilities.To achieve this,the robot employs a novel combination of a jumping module and a crawling module.The jumping module features improved energy storage capacity and an active clutch.Within the constraints of structural robustness,the jumping module maximizes the explosive power of the linear spring by utilizing the mechanical advantage of a closed-loop mechanism and controls the energy flow of the jumping module through an active clutch mechanism.Furthermore,inspired by the limb movements of tortoises during crawling and self-righting,a single-degree-of-freedom spatial four-bar crawling mechanism was designed to enable crawling,steering,and resetting functions.To demonstrate its practicality,the integrated jumping-crawling robot was tested in a laboratory environment for functions such as jumping,crawling,self-resetting,and steering.Experimental results confirmed the feasibility of the proposed integrated jumping-crawling robot.
文摘This paper is concerned with the reflected stochastic Burgers equation driven both by the Brownian motion and by the Poisson random measure.The existence and uniqueness of solutions are established.The penalization method plays an important role.
基金supported by the National Natural Science Foundation of China(No.32270460).
文摘Bio-inspired jumping robots have emerged as a promising solution for traversing complex terrains inaccessible to conventional locomotion systems.Drawing upon the exceptional jumping kinematics observed in insects,researchers have developed multiple robotic prototypes mimicking biological propulsion mechanisms.However,the principal technological barrier resides in actuator systems,where current energy storage technologies suffer from inadequate energy density,fundamentally limiting takeoff velocity and jumping height.To overcome these limitations,we present a novel combustion-explosive propulsion system exhibiting high mass-specific energy release and rapid acceleration characteristics.By integrating this propulsion mechanism with a unique jumping leg structure,experimental validation through prototype testing demonstrated vertical leaps reaching 20 cm(1.67 times body length)under laboratory conditions,accompanied by comprehensive thermodynamic modeling using ABAQUS simulations that validated the effectiveness of this actuation system.The integrated design approach combines bionic structural design with combustible fuel formulations to offer new possibilities for the development of highly flexible robotic systems capable of negotiating obstacles in disaster response scenarios.
基金Supported by New Chongqing Innovative Young Talent Project(Grant No.2024NSCQ-qncxX0468)Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQ-MSX1283)Dreams Foundation of Jianghuai Advanced Technology Center(Grant No.2023-ZM01Z007).
文摘Jumping robots are highly capable of overcoming obstacles.However,their explosive force,short duration,and variable trajectories pose significant challenges in achieving stable landings in complex environments.Traditional approaches rely heavily on sophisticated algorithms and electronic sensor feedback systems to ensure landing stability,which increases the implementation complexity.Inspired by the process by which humans complete jumps and achieve stable landings in complex environments,this study proposes a novel landing control method for jumping robots.By designing a mechanically coupled perception-control structure based on mechanical logic computing,the robot simulates the real-time transmission of neural signals triggered by the ground reaction force(GRF)in human reflex loops,thereby simplifying traditional control approaches.Through the collaboration of a flexible mechanical spine and a bistable foot module,the robot achieves an average height of 16.8 cm and a distance of 25.36 cm in consecutive stable jumps.It also demonstrates reliable landing performance on challenging terrain including slopes and cobblestone surfaces.This paper proposes a novel landing control method for jumping robots that simplifies traditional control approaches.The method enables stable landings on complex terrain through a mechanically coupled perception-control structure.This approach has potential applications in tasks requiring mobility over uneven terrain,such as search and rescue.
文摘ClO4)2 (MnCP),(ClO4)2 (NiCP) and (ClO4) 2 (PbCP) (CHZ=Carbohydrazide) were flash pyrolyzed at different temperatures und er the set pressure by T-jump/FTIR spectroscopy. The results show that twelve ga s products obtained during the flash pyrolysis process of the three complexes we re CO2, CO, HCl, HCN, NH3, NO2, N2O, NO, HNCO, HONO, H2C=O and H2O, of which CO2 , HCN and HCl were the main gas products and CO2 was the most novel product. NH3 was oxidized to NO2, N2O and H2O. At least some of the N2O might result from th is reaction. Additionally, the effect of temperature on the gas products is disc ussed and the concentration-time change curves of the main gas products are give n.
文摘背景:肢体间不对称是人类生长发育过程中的一般现象,长期专项训练可使运动员肢体间不对称发生特异性适应。目的:回顾了体育运动中肢体间不对称的形成原因、表现形式及对运动能力的影响,并概述了相关评估方法及干预策略。方法:检索中国知网、万方、PubMed及Web of Science数据库建库至2024年9月间收录的文献,中文检索词为“不对称,对称,失衡,平衡,力量,爆发力,跳跃,跑,人体测量学,运动损伤,运动能力,运动表现”,英文检索词为“asymmetry,asymmetries,asymmetric,asymmetrical,imbalance,strength,power,force,jump,sprint,athletic performance,anthropometry,injury”。排除重复发表、内容不相关及会议文献后,最终纳入131篇文献进行分析。结果与结论:(1)肢体间不对称可受遗传、任务、训练、损伤、疲劳和肢体偏好等因素影响,主要表现为解剖结构、力量表现、专项任务不对称等形式;(2)肢体间不对称增大可导致双侧同相位对称类运动能力受损,但与双侧异相位对称类运动能力间关系尚不明确;(3)训练干预可有效改善肢体间不对称,且单侧训练效果优于双侧,训练方式和内容选择应符合专项需求;(4)为进一步厘清肢体间不对称与运动能力间的关系,建议未来研究秉承肢体间不对称的“任务特异性”理念,规范研究设计,选择敏感测试手段与指标,统一计算方式以提供更多的高质量证据,并分类制定不同专项肢体间不对称的预警阈值标准。
文摘Using conventional mathematical statistics,linear regression and the standard deviation,the quantitative analysis was made on the climate changes in Shenyang.The results showed that the trend of precipitation reduced 155 mm,which was made the greatest contribution by summer and autumn.It decreased 43 mm on the average after the climate jump.The precipitation variability in spring increased and drought risk in spring increased.The first soaking rain limited the spring planting time.The temperature trend raised 1.3℃,mainly in spring and winter.The frost-free period extended about 13 d.The accumulated temperature trends in crop growing season increased 290℃ and it had an average increase of 178℃ after the climate jump.This trend of climate warming made the end of last frost advanced.Early sowing of crops suitably was possible,which was beneficial for agricultural production.The precipitation decrease,the time delay and instability of the first soaking rain were unfavorable for crop growth and seeding.And they became the factors that constrained the normal growth and stabile yield raise of crops.
基金Supported by the National Natural Science Foundation of China(11271312,11261056)the China Postdoctoral Science Foundation(20110491750,2012T50836)the Natural Science Foundation of Xinjiang(2011211B08)
