This paper presents the development of a mesoscale self-contained quadruped mobile robot that employs two pieces of piezocomposite actuators for the bounding locomotion.The design of the robot leg is inspired by legge...This paper presents the development of a mesoscale self-contained quadruped mobile robot that employs two pieces of piezocomposite actuators for the bounding locomotion.The design of the robot leg is inspired by legged insects and animals, and the biomimetic concept is implemented in the robot in a simplified form,such that each leg of the robot has only one degree of freedom.The lack of degree of freedom is compensated by a slope of the robot frame relative to the horizontal plane.For the implementation of the self-contained mobile robot,a small power supply circuit is designed and installed on the robot.Experimental results show that the robot can locomote at about 50 mm·s^(-1)with the circuit on board,which can be considered as a significant step toward the goal of building an autonomous legged robot actuated by piezoelectric actuators.展开更多
Firefighters’low back disorders(LBDs)are closely related to excessive spine loading when using the self-contained breathing apparatus(SCBA)continuously.The purpose of this study was to quantify firefighters’spine lo...Firefighters’low back disorders(LBDs)are closely related to excessive spine loading when using the self-contained breathing apparatus(SCBA)continuously.The purpose of this study was to quantify firefighters’spine loading and evaluate the effects of strap lengths of SCBA on altering spine loading.Computer-based musculoskeletal models of three varying-strapped SCBA conditions and a control condition(CC)with no SCBA equipped were developed.The model was driven using three-dimensional(3 D)inertial motion capture data from twelve male subjects performing a walking task and the predicted ground reaction force(GRF).Electromyography(EMG)activities were also recorded to validate the results from the model.The 4 th-5 th lumbar vertebra(L4/L5)joint reaction forces,as well as erector spinae and rectus abdominis forces,were finally obtained.Results demonstrated that carrying SCBA significantly increased the compressive force and anteroposterior shear force at the spine.The risk of potential LBDs increased by about 17.77%.Dynamic balance of erector spinae and rectus abdominis contraction was also disturbed when carrying SCBA,indicating a higher risk of spine muscle strain.Adjustment of SCBA strap length was an efficient method to influence spine loading.The medium-fitting strap(MS)with a length of around 101 cm generated minimum joint reaction forces and achieved the optimum dynamic balance of spine muscle contraction,which was recommended for firefighters.展开更多
This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas-tight oil/gas-shale oil/gas sequential accumulation and the hydrocarbon accumulation ...This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas-tight oil/gas-shale oil/gas sequential accumulation and the hydrocarbon accumulation models and mechanisms of the whole petroleum system.It delineates the geological model,flow model,and production mechanism of shale and tight reservoirs,and proposes future research orientations.The main structure of the whole petroleum system includes three fluid dynamic fields,three types of oil and gas reservoirs/resources,and two types of reservoir-forming processes.Conventional oil/gas,tight oil/gas,and shale oil/gas are orderly in generation time and spatial distribution,and sequentially rational in genetic mechanism,showing the pattern of sequential accumulation.The whole petroleum system involves two categories of hydrocarbon accumulation models:hydrocarbon accumulation in the detrital basin and hydrocarbon accumulation in the carbonate basin/formation.The accumulation of unconventional oil/gas is self-containment,which is microscopically driven by the intermolecular force(van der Waals force).The unconventional oil/gas production has proved that the geological model,flow model,and production mechanism of shale and tight reservoirs represent a new and complex field that needs further study.Shale oil/gas must be the most important resource replacement for oil and gas resources of China.Future research efforts include:(1)the characteristics of the whole petroleum system in carbonate basins and the source-reservoir coupling patterns in the evolution of composite basins;(2)flow mechanisms in migration,accumulation,and production of shale oil/gas and tight oil/gas;(3)geological characteristics and enrichment of deep and ultra-deep shale oil/gas,tight oil/gas and coalbed methane;(4)resource evaluation and new generation of basin simulation technology of the whole petroleum system;(5)research on earth system-earth organic rock and fossil fuel system-whole petroleum system.展开更多
随着我国交流特高压电网的发展,交流特高压输电技术的试验研究以及交流特高压设备的绝缘考核都需要特高压交流试验电源。针对传统调频谐振式特高压试验电源(UHV frequency tuned resonant test power supply,UHV-FTRTPS)的缺点,结合现...随着我国交流特高压电网的发展,交流特高压输电技术的试验研究以及交流特高压设备的绝缘考核都需要特高压交流试验电源。针对传统调频谐振式特高压试验电源(UHV frequency tuned resonant test power supply,UHV-FTRTPS)的缺点,结合现有的电力电子技术,对其整体拓扑结构进行了设计,在深入分析整个系统频率特性的基础上,确定频率上、下限分别为30和300Hz,提出特高压试验电源的主要组成部分的参数设计方案,并以该方案为基础设计一套调频谐振式特高压试验电源装置。实验结果表明,以该方法设计的特高压试验电源装置参数合理,符合设计要求,可满足交流特高压试验研究的需求,对其工程应用及产品化还可起到一定的指导和借鉴作用。展开更多
指出在高速铁路牵引供电系统故障诊断中应计及所获取的保护和开关动作信息的不确信性和模糊性,基于此,将模糊Petri网(fuzzy Petri net,FPN)应用于牵引供电系统的故障诊断。考虑到牵引供电系统保护的特殊性,进行了第2次推理;针对越区供...指出在高速铁路牵引供电系统故障诊断中应计及所获取的保护和开关动作信息的不确信性和模糊性,基于此,将模糊Petri网(fuzzy Petri net,FPN)应用于牵引供电系统的故障诊断。考虑到牵引供电系统保护的特殊性,进行了第2次推理;针对越区供电时馈线远后备保护覆盖元件多的特点,增加了推理条件以保证推理的正确性;根据供电臂故障特征,给出了供电臂故障区间判别规则。算例分析结果表明,牵引供电系统的模糊Petri网故障诊断方法简洁、推理直观,能够在不确定或信息缺失的情况下,提高故障区域判断的确信性。展开更多
针对部分输变电设备智能监测传感器存在的电源不易获取、现有供电方案可靠性差这一问题,提出了利用环境能量收集技术,采集并转换热电、磁场能量,从而实现智能传感器工作能量自给的方法。通过理论计算分别对上述两种能量收集方法进行了...针对部分输变电设备智能监测传感器存在的电源不易获取、现有供电方案可靠性差这一问题,提出了利用环境能量收集技术,采集并转换热电、磁场能量,从而实现智能传感器工作能量自给的方法。通过理论计算分别对上述两种能量收集方法进行了可行性分析,通过取能实验研究了其输出特性,并采用Zigbee无线传感器节点进行了带载实验。计算及实验结果表明:在该研究条件下,利用油浸式变压器箱体产生的热量,当其上附着的热电模块冷热端温差达55 K时,热电能量收集能获得475 m W的最大输出功率;利用安装于35 k V母线排表面的取能线圈,当母排电流达到480 A时,可驱动Zigbee节点连续工作,此时,磁场能量收集能获得163 m W的最大输出功率。通过结合上述两种在电网中可行性较高的能量收集方法为传感器提供电源,能满足大部分低功耗智能传感器节点的能耗需求,具有一定的应用前景。展开更多
针对新型调频式谐振特高压试验电源(UHV frequencytuned resonant test power supply,UHV-FTRTPS)输出信号频率较宽,不易获得最佳波形这一问题,提出了一种新的特高压试验电源方案。在167～300 Hz高频率段,采用同步正弦脉宽调制(sinusoid...针对新型调频式谐振特高压试验电源(UHV frequencytuned resonant test power supply,UHV-FTRTPS)输出信号频率较宽,不易获得最佳波形这一问题,提出了一种新的特高压试验电源方案。在167～300 Hz高频率段,采用同步正弦脉宽调制(sinusoidal pulse-width modulation,SPWM),把载波比N的数值选择与输出滤波器本身结构相结合,得到合理的最佳N值和滤波器最小视在功率。同时,在30～167 Hz低频率段,采用特定次谐波消除方法在线计算各开关角度,消弱低次谐波,把低次谐波转移到高次谐波,以利于输出滤波器滤除。最后,在输出滤波器电容上串联1个虚拟电阻,在不增加硬件及不改变输出滤波器结构的基础上,从软件控制方法上来增强其阻尼性,使之更好地滤除高次谐波。仿真及试验结果验证了该方案的正确性和有效性,对新型特高压试验电源的工程应用及产品化具有一定的指导和借鉴作用。展开更多
基金supported by Korea Research Foundation grant(KRF-2006-005-J03303)and Seoul R&BD Program
文摘This paper presents the development of a mesoscale self-contained quadruped mobile robot that employs two pieces of piezocomposite actuators for the bounding locomotion.The design of the robot leg is inspired by legged insects and animals, and the biomimetic concept is implemented in the robot in a simplified form,such that each leg of the robot has only one degree of freedom.The lack of degree of freedom is compensated by a slope of the robot frame relative to the horizontal plane.For the implementation of the self-contained mobile robot,a small power supply circuit is designed and installed on the robot.Experimental results show that the robot can locomote at about 50 mm·s^(-1)with the circuit on board,which can be considered as a significant step toward the goal of building an autonomous legged robot actuated by piezoelectric actuators.
基金Fundamental Research Funds for the Central Universities,China(No.2232022G-08)。
文摘Firefighters’low back disorders(LBDs)are closely related to excessive spine loading when using the self-contained breathing apparatus(SCBA)continuously.The purpose of this study was to quantify firefighters’spine loading and evaluate the effects of strap lengths of SCBA on altering spine loading.Computer-based musculoskeletal models of three varying-strapped SCBA conditions and a control condition(CC)with no SCBA equipped were developed.The model was driven using three-dimensional(3 D)inertial motion capture data from twelve male subjects performing a walking task and the predicted ground reaction force(GRF).Electromyography(EMG)activities were also recorded to validate the results from the model.The 4 th-5 th lumbar vertebra(L4/L5)joint reaction forces,as well as erector spinae and rectus abdominis forces,were finally obtained.Results demonstrated that carrying SCBA significantly increased the compressive force and anteroposterior shear force at the spine.The risk of potential LBDs increased by about 17.77%.Dynamic balance of erector spinae and rectus abdominis contraction was also disturbed when carrying SCBA,indicating a higher risk of spine muscle strain.Adjustment of SCBA strap length was an efficient method to influence spine loading.The medium-fitting strap(MS)with a length of around 101 cm generated minimum joint reaction forces and achieved the optimum dynamic balance of spine muscle contraction,which was recommended for firefighters.
基金Supported by the National Natural Science Foundation of China(U22B6002)PetroChina Science Research and Technology Development Project(2021DJ0101)。
文摘This paper expounds the basic principles and structures of the whole petroleum system to reveal the pattern of conventional oil/gas-tight oil/gas-shale oil/gas sequential accumulation and the hydrocarbon accumulation models and mechanisms of the whole petroleum system.It delineates the geological model,flow model,and production mechanism of shale and tight reservoirs,and proposes future research orientations.The main structure of the whole petroleum system includes three fluid dynamic fields,three types of oil and gas reservoirs/resources,and two types of reservoir-forming processes.Conventional oil/gas,tight oil/gas,and shale oil/gas are orderly in generation time and spatial distribution,and sequentially rational in genetic mechanism,showing the pattern of sequential accumulation.The whole petroleum system involves two categories of hydrocarbon accumulation models:hydrocarbon accumulation in the detrital basin and hydrocarbon accumulation in the carbonate basin/formation.The accumulation of unconventional oil/gas is self-containment,which is microscopically driven by the intermolecular force(van der Waals force).The unconventional oil/gas production has proved that the geological model,flow model,and production mechanism of shale and tight reservoirs represent a new and complex field that needs further study.Shale oil/gas must be the most important resource replacement for oil and gas resources of China.Future research efforts include:(1)the characteristics of the whole petroleum system in carbonate basins and the source-reservoir coupling patterns in the evolution of composite basins;(2)flow mechanisms in migration,accumulation,and production of shale oil/gas and tight oil/gas;(3)geological characteristics and enrichment of deep and ultra-deep shale oil/gas,tight oil/gas and coalbed methane;(4)resource evaluation and new generation of basin simulation technology of the whole petroleum system;(5)research on earth system-earth organic rock and fossil fuel system-whole petroleum system.
文摘随着我国交流特高压电网的发展,交流特高压输电技术的试验研究以及交流特高压设备的绝缘考核都需要特高压交流试验电源。针对传统调频谐振式特高压试验电源(UHV frequency tuned resonant test power supply,UHV-FTRTPS)的缺点,结合现有的电力电子技术,对其整体拓扑结构进行了设计,在深入分析整个系统频率特性的基础上,确定频率上、下限分别为30和300Hz,提出特高压试验电源的主要组成部分的参数设计方案,并以该方案为基础设计一套调频谐振式特高压试验电源装置。实验结果表明,以该方法设计的特高压试验电源装置参数合理,符合设计要求,可满足交流特高压试验研究的需求,对其工程应用及产品化还可起到一定的指导和借鉴作用。
文摘指出在高速铁路牵引供电系统故障诊断中应计及所获取的保护和开关动作信息的不确信性和模糊性,基于此,将模糊Petri网(fuzzy Petri net,FPN)应用于牵引供电系统的故障诊断。考虑到牵引供电系统保护的特殊性,进行了第2次推理;针对越区供电时馈线远后备保护覆盖元件多的特点,增加了推理条件以保证推理的正确性;根据供电臂故障特征,给出了供电臂故障区间判别规则。算例分析结果表明,牵引供电系统的模糊Petri网故障诊断方法简洁、推理直观,能够在不确定或信息缺失的情况下,提高故障区域判断的确信性。
文摘针对部分输变电设备智能监测传感器存在的电源不易获取、现有供电方案可靠性差这一问题,提出了利用环境能量收集技术,采集并转换热电、磁场能量,从而实现智能传感器工作能量自给的方法。通过理论计算分别对上述两种能量收集方法进行了可行性分析,通过取能实验研究了其输出特性,并采用Zigbee无线传感器节点进行了带载实验。计算及实验结果表明:在该研究条件下,利用油浸式变压器箱体产生的热量,当其上附着的热电模块冷热端温差达55 K时,热电能量收集能获得475 m W的最大输出功率;利用安装于35 k V母线排表面的取能线圈,当母排电流达到480 A时,可驱动Zigbee节点连续工作,此时,磁场能量收集能获得163 m W的最大输出功率。通过结合上述两种在电网中可行性较高的能量收集方法为传感器提供电源,能满足大部分低功耗智能传感器节点的能耗需求,具有一定的应用前景。
文摘针对新型调频式谐振特高压试验电源(UHV frequencytuned resonant test power supply,UHV-FTRTPS)输出信号频率较宽,不易获得最佳波形这一问题,提出了一种新的特高压试验电源方案。在167～300 Hz高频率段,采用同步正弦脉宽调制(sinusoidal pulse-width modulation,SPWM),把载波比N的数值选择与输出滤波器本身结构相结合,得到合理的最佳N值和滤波器最小视在功率。同时,在30～167 Hz低频率段,采用特定次谐波消除方法在线计算各开关角度,消弱低次谐波,把低次谐波转移到高次谐波,以利于输出滤波器滤除。最后,在输出滤波器电容上串联1个虚拟电阻,在不增加硬件及不改变输出滤波器结构的基础上,从软件控制方法上来增强其阻尼性,使之更好地滤除高次谐波。仿真及试验结果验证了该方案的正确性和有效性,对新型特高压试验电源的工程应用及产品化具有一定的指导和借鉴作用。
