Based on nominal model, a novel global sliding mode controller （GSMC） with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is th...Based on nominal model, a novel global sliding mode controller （GSMC） with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is the global sliding mode controller for practical plant, the other is the integral backstepping controller for nominal model. Modeling error between practical plant and nominal model is used to design GSMC. The steady-state control accuracy can be guaranteed by the integral backstepping control law, and the global robustness can be obtained by GSMC. The stability of the proposed controller is proved according to the Lyapunov approach. The simulation results both of sine signal and step signal tracking for 3-axis flight table are investigated to show good position tracking performance and high robustness with respect to large and parameter changes over all the response time.展开更多
Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexi...Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexible assembly system is just beginning in our country recently. To meet the requirements of automated posture alignment and join in digital assembly system for large aircraft components, a novel fitting fixture called 3-axis actuator is developed. On the basis of the actuators, three kinds of posture alignment system for large aircraft components are proposed, including the non-redundant system, the redundant actuating system, and the redundant leg system, and their constitutions and properties are introduced. Through deriving the feeding transmission stiffness model of single actuator and analyzing the inverse kinematics of these systems, the relationship between the external force and the changes of position and orientation of large aircraft component is obtained, and then the postural alignment stiffness models are established. With the method mentioned above, the postural alignment stiffness of three systems is computed by using the algebraic formulate, and the results show that redundant properties can increase system＇s postural alignment stiffness. As an example, a optimized layout of the assembly system for a given model of aircraft is developed, the results of application show that the layout has many advantages, such as high accuracy, stiffness, stability, reliability, efficiency and flexible, which can satisfy the requirement of aircraft digital assembly system well. The proposed study of postural alignment stiffness for different systems can supply the theoretic support for the optimization layout design of aircraft digital assembly system, and contribute to evaluate the system working performance of systems.展开更多
The 3-axis flight table is an important device and a typical high performanceposition and speed servo system used in the hardware-in-the-loop simulation of flight controlsystem. Friction force and uncertainty are the ...The 3-axis flight table is an important device and a typical high performanceposition and speed servo system used in the hardware-in-the-loop simulation of flight controlsystem. Friction force and uncertainty are the main characteristics in the 3-axis flight table servosystem. Based on the description of dynamic and static model of a nonlinear Stribeck frictionmodel, and taking account of the practical uncertainties of 3-axis flight table servo system, theQFT controller is designed. Simulation and realtime results are presented.展开更多
Human pose estimation is a basic and critical task in the field of computer vision that involves determining the position(or spatial coordinates)of the joints of the human body in a given image or video.It is widely u...Human pose estimation is a basic and critical task in the field of computer vision that involves determining the position(or spatial coordinates)of the joints of the human body in a given image or video.It is widely used in motion analysis,medical evaluation,and behavior monitoring.In this paper,the authors propose a method for multi-view human pose estimation.Two image sensors were placed orthogonally with respect to each other to capture the pose of the subject as they moved,and this yielded accurate and comprehensive results of three-dimensional(3D)motion reconstruction that helped capture their multi-directional poses.Following this,we propose a method based on 3D pose estimation to assess the similarity of the features of motion of patients with motor dysfunction by comparing differences between their range of motion and that of normal subjects.We converted these differences into Fugl–Meyer assessment(FMA)scores in order to quantify them.Finally,we implemented the proposed method in the Unity framework,and built a Virtual Reality platform that provides users with human–computer interaction to make the task more enjoyable for them and ensure their active participation in the assessment process.The goal is to provide a suitable means of assessing movement disorders without requiring the immediate supervision of a physician.展开更多
This paper demonstrated our discovery of the movement effect of BiFeO_3 nanoparticles in solution by strong electrical polarization. First, BiFeO_3 nanoparticles were prepared by ball milling and characterized by SEM....This paper demonstrated our discovery of the movement effect of BiFeO_3 nanoparticles in solution by strong electrical polarization. First, BiFeO_3 nanoparticles were prepared by ball milling and characterized by SEM. Then, the preparation of BiFeO_3 solution was finished. BiFeO_3 nanoparticles are found to move in solution due to electrical field. The movement velocity of BiFeO_3 nanoparticles, which is about 10 μm·s^-1 , is influenced and controlled by the applied electrical field. The concentration of BiFeO_3 solution and the nanoparticle sizes also have effects on its movement properties. The movement of BiFeO_3 nanoparticles in solution is induced by strong polarization, and BiFeO_3 nanoparticles have net negative electric charges because of the electrostatic force between BiFeO_3 nanoparticles and the negative ions in water resolver.展开更多
The characteristics of the present-day crustal three dimensional (3D) movement with GNSS data during 1999-2018 and the precise leveling data during 1970s-2018 in Hainan Island and its adjacent area are analyzed. Based...The characteristics of the present-day crustal three dimensional (3D) movement with GNSS data during 1999-2018 and the precise leveling data during 1970s-2018 in Hainan Island and its adjacent area are analyzed. Based on the data and the horizontal movement field in the region of Southeast Asia, we discuss how the horizontal velocities in Hainan and the continental margin of the South China block (SCB) are affected by the Eurasian plate, the India-Australia plate and the Philippine Sea plate. The results show the movement of Hainan Island is the same as SCB. The horizontal velocities of the continental margin in South China are different in the east and the west along the boundary of the Northeastern Coast block and Yangtze Block. In Hainan Island, the 3D movement is different in two regions divided by Baisha fault. The movement of SCB is affected by Indo-European collision and extrusion. The movement of the continental margin is affected by both the Pacific Ocean plate, the Philippine Sea plate, the expansion of the South China Sea (SCS), the hot materials underplating and subsequent lithospheric extension. The effect on the regional movement by the Australia plate is smaller, but it can cause co-seismic step to SCB when there had a giant earthquake in Sumatra which is caused by the convergence of the Australia with the Sunda Plate in the NE direction.展开更多
Identification of magnitude and orientation for spatially applied loading is highly desired in the fields of not only the machinery components but also human-machine interaction.Despite the fact that the 3-axis force ...Identification of magnitude and orientation for spatially applied loading is highly desired in the fields of not only the machinery components but also human-machine interaction.Despite the fact that the 3-axis force sensor with different structures has been proposed to measure the spatial force,there are still some common limitations including the multi-step manufacturing-assembly processes and complicated testing of decoupling calibration.Here,we propose a rapid fabrication strategy with low-cost to achieve high-precision 3-axis force sensors.The sensor is designed to compose of structural Maltese cross base and sensing units.It is directly fabricated within one step by a hybrid 3D printing technology combining deposition modeling(FDM)with direct-ink-writing(DIW).In particular,a machine learning(ML)model is used to convert the strain signal to the force components.Instead of a mount of calibration tests,this ML model is trained by sufficient simulation data based on programmed batch finite element modeling.This sensor is capable of continuously identifying a spatial force with varying magnitude and orientation,which successfully quantify the applied force of traditional Chinese medicine physiotherapy including Gua Sha and massage.This work provides insight for design and rapid fabrication of multi-axis force sensors,as well as potential applications.展开更多
目的观察意向运动疗法对脑缺血再灌注损伤后缺血区脑组织NT-3及GAP-43蛋白表达的影响,探讨意向运动疗法对神经再生和修复的作用。方法运用线栓法制备大鼠大脑中动脉缺血再灌注损伤模型,随机分为大脑中动脉栓塞模型组(MCAO组)、饲养环境...目的观察意向运动疗法对脑缺血再灌注损伤后缺血区脑组织NT-3及GAP-43蛋白表达的影响,探讨意向运动疗法对神经再生和修复的作用。方法运用线栓法制备大鼠大脑中动脉缺血再灌注损伤模型,随机分为大脑中动脉栓塞模型组(MCAO组)、饲养环境改变组(EM组)、意向运动疗法组(WM组),再灌注后3、7、15 d 3个时间点进行神经功能缺损评分、免疫组化法检测脑缺血区脑组织NT-3、GAP-43蛋白的表达。结果再灌注15 d时WM组神经功能缺损评分显著低于MCAO组及EM组(P<0.05);再灌注7、15 d时WM组的NT-3及GAP-43蛋白表达均显著高于MCAO组和EM组(P<0.05);EM组与MCAO组比较:NT-3及GAP-43蛋白的表达无明显差异(P>0.05);NT-3与GAP-43蛋白的表达变化呈正相关。结论意向运动疗法可促进脑缺血再灌注损伤大鼠缺血区脑组织NT-3、GAP-43蛋白的表达,可能与缺血损伤神经元的再生和修复有关。展开更多
目的:分析儿童体质测试成绩与粗大动作技能发展之间的关系,对不同儿童进行有针对性的指导和帮助。方法:北京市4所幼儿园共1 928名儿童,按照《国民体质测定标准手册》(幼儿部分)进行体质测试。随机整群选取了8个班作为整群对照(CG,n=244)...目的:分析儿童体质测试成绩与粗大动作技能发展之间的关系,对不同儿童进行有针对性的指导和帮助。方法:北京市4所幼儿园共1 928名儿童,按照《国民体质测定标准手册》(幼儿部分)进行体质测试。随机整群选取了8个班作为整群对照(CG,n=244),并根据体质测试成绩,选取成绩前10%的儿童(TG,n=203)和后10%儿童(BG,n=203),采用Test of Gross Motor Development-3(TGMD-3)对儿童粗大动作发展进行评估,对移动类和球类技能两大类基本动作的动作技能进行评估。结果:1)男童移动动作分值与女童无明显差别;2)男童球类动作技能好于女童,且随年龄增加其优势更加明显;3)体质测试成绩差的儿童,动作发展低于整体水平,特别是其球类动作技能的发展;4)随着年龄的增长,儿童动作发展的差距随年龄增长有逐渐扩大的趋势;5)粗大动作发展与体质测试结果中等相关。结论:针对3~6岁儿童,促进其体质发展,必须重视儿童动作技能的发展,对动作技能发展滞后的儿童应在教学活动中给予更多关注和指导。展开更多
文摘Based on nominal model, a novel global sliding mode controller （GSMC） with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is the global sliding mode controller for practical plant, the other is the integral backstepping controller for nominal model. Modeling error between practical plant and nominal model is used to design GSMC. The steady-state control accuracy can be guaranteed by the integral backstepping control law, and the global robustness can be obtained by GSMC. The stability of the proposed controller is proved according to the Lyapunov approach. The simulation results both of sine signal and step signal tracking for 3-axis flight table are investigated to show good position tracking performance and high robustness with respect to large and parameter changes over all the response time.
文摘Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexible assembly system is just beginning in our country recently. To meet the requirements of automated posture alignment and join in digital assembly system for large aircraft components, a novel fitting fixture called 3-axis actuator is developed. On the basis of the actuators, three kinds of posture alignment system for large aircraft components are proposed, including the non-redundant system, the redundant actuating system, and the redundant leg system, and their constitutions and properties are introduced. Through deriving the feeding transmission stiffness model of single actuator and analyzing the inverse kinematics of these systems, the relationship between the external force and the changes of position and orientation of large aircraft component is obtained, and then the postural alignment stiffness models are established. With the method mentioned above, the postural alignment stiffness of three systems is computed by using the algebraic formulate, and the results show that redundant properties can increase system＇s postural alignment stiffness. As an example, a optimized layout of the assembly system for a given model of aircraft is developed, the results of application show that the layout has many advantages, such as high accuracy, stiffness, stability, reliability, efficiency and flexible, which can satisfy the requirement of aircraft digital assembly system well. The proposed study of postural alignment stiffness for different systems can supply the theoretic support for the optimization layout design of aircraft digital assembly system, and contribute to evaluate the system working performance of systems.
文摘The 3-axis flight table is an important device and a typical high performanceposition and speed servo system used in the hardware-in-the-loop simulation of flight controlsystem. Friction force and uncertainty are the main characteristics in the 3-axis flight table servosystem. Based on the description of dynamic and static model of a nonlinear Stribeck frictionmodel, and taking account of the practical uncertainties of 3-axis flight table servo system, theQFT controller is designed. Simulation and realtime results are presented.
基金This work was supported by grants fromthe Natural Science Foundation of Hebei Province,under Grant No.F2021202021the S&T Program of Hebei,under Grant No.22375001Dthe National Key R&D Program of China,under Grant No.2019YFB1312500.
文摘Human pose estimation is a basic and critical task in the field of computer vision that involves determining the position(or spatial coordinates)of the joints of the human body in a given image or video.It is widely used in motion analysis,medical evaluation,and behavior monitoring.In this paper,the authors propose a method for multi-view human pose estimation.Two image sensors were placed orthogonally with respect to each other to capture the pose of the subject as they moved,and this yielded accurate and comprehensive results of three-dimensional(3D)motion reconstruction that helped capture their multi-directional poses.Following this,we propose a method based on 3D pose estimation to assess the similarity of the features of motion of patients with motor dysfunction by comparing differences between their range of motion and that of normal subjects.We converted these differences into Fugl–Meyer assessment(FMA)scores in order to quantify them.Finally,we implemented the proposed method in the Unity framework,and built a Virtual Reality platform that provides users with human–computer interaction to make the task more enjoyable for them and ensure their active participation in the assessment process.The goal is to provide a suitable means of assessing movement disorders without requiring the immediate supervision of a physician.
基金supported by the National Natural Science Foundation of China(No.50807042)the Research Fund for the Doctoral Program of Higher Education of China(No.200806981043)+1 种基金the Fundamental Research Fund for the Central Universities(No.xjj2012088)the fund of StateKey Laboratory of Electrical Insulation and Power Equipment(Xi'an Jiaotong University No.EIPE12305)
文摘This paper demonstrated our discovery of the movement effect of BiFeO_3 nanoparticles in solution by strong electrical polarization. First, BiFeO_3 nanoparticles were prepared by ball milling and characterized by SEM. Then, the preparation of BiFeO_3 solution was finished. BiFeO_3 nanoparticles are found to move in solution due to electrical field. The movement velocity of BiFeO_3 nanoparticles, which is about 10 μm·s^-1 , is influenced and controlled by the applied electrical field. The concentration of BiFeO_3 solution and the nanoparticle sizes also have effects on its movement properties. The movement of BiFeO_3 nanoparticles in solution is induced by strong polarization, and BiFeO_3 nanoparticles have net negative electric charges because of the electrostatic force between BiFeO_3 nanoparticles and the negative ions in water resolver.
文摘The characteristics of the present-day crustal three dimensional (3D) movement with GNSS data during 1999-2018 and the precise leveling data during 1970s-2018 in Hainan Island and its adjacent area are analyzed. Based on the data and the horizontal movement field in the region of Southeast Asia, we discuss how the horizontal velocities in Hainan and the continental margin of the South China block (SCB) are affected by the Eurasian plate, the India-Australia plate and the Philippine Sea plate. The results show the movement of Hainan Island is the same as SCB. The horizontal velocities of the continental margin in South China are different in the east and the west along the boundary of the Northeastern Coast block and Yangtze Block. In Hainan Island, the 3D movement is different in two regions divided by Baisha fault. The movement of SCB is affected by Indo-European collision and extrusion. The movement of the continental margin is affected by both the Pacific Ocean plate, the Philippine Sea plate, the expansion of the South China Sea (SCS), the hot materials underplating and subsequent lithospheric extension. The effect on the regional movement by the Australia plate is smaller, but it can cause co-seismic step to SCB when there had a giant earthquake in Sumatra which is caused by the convergence of the Australia with the Sunda Plate in the NE direction.
基金supported by the National Natural Science Foundation of China [12372078]Sixth Phase of Jiangsu Province"333 High Level Talent Training Project"Second Level Talents State Key Laboratory of Mechanics and Control of Mechanical Structures (Nanjing University of Aeronautics and astronautics [MCMS-E-0422G04].
文摘Identification of magnitude and orientation for spatially applied loading is highly desired in the fields of not only the machinery components but also human-machine interaction.Despite the fact that the 3-axis force sensor with different structures has been proposed to measure the spatial force,there are still some common limitations including the multi-step manufacturing-assembly processes and complicated testing of decoupling calibration.Here,we propose a rapid fabrication strategy with low-cost to achieve high-precision 3-axis force sensors.The sensor is designed to compose of structural Maltese cross base and sensing units.It is directly fabricated within one step by a hybrid 3D printing technology combining deposition modeling(FDM)with direct-ink-writing(DIW).In particular,a machine learning(ML)model is used to convert the strain signal to the force components.Instead of a mount of calibration tests,this ML model is trained by sufficient simulation data based on programmed batch finite element modeling.This sensor is capable of continuously identifying a spatial force with varying magnitude and orientation,which successfully quantify the applied force of traditional Chinese medicine physiotherapy including Gua Sha and massage.This work provides insight for design and rapid fabrication of multi-axis force sensors,as well as potential applications.
文摘目的观察意向运动疗法对脑缺血再灌注损伤后缺血区脑组织NT-3及GAP-43蛋白表达的影响,探讨意向运动疗法对神经再生和修复的作用。方法运用线栓法制备大鼠大脑中动脉缺血再灌注损伤模型,随机分为大脑中动脉栓塞模型组(MCAO组)、饲养环境改变组(EM组)、意向运动疗法组(WM组),再灌注后3、7、15 d 3个时间点进行神经功能缺损评分、免疫组化法检测脑缺血区脑组织NT-3、GAP-43蛋白的表达。结果再灌注15 d时WM组神经功能缺损评分显著低于MCAO组及EM组(P<0.05);再灌注7、15 d时WM组的NT-3及GAP-43蛋白表达均显著高于MCAO组和EM组(P<0.05);EM组与MCAO组比较:NT-3及GAP-43蛋白的表达无明显差异(P>0.05);NT-3与GAP-43蛋白的表达变化呈正相关。结论意向运动疗法可促进脑缺血再灌注损伤大鼠缺血区脑组织NT-3、GAP-43蛋白的表达,可能与缺血损伤神经元的再生和修复有关。
文摘目的:分析儿童体质测试成绩与粗大动作技能发展之间的关系,对不同儿童进行有针对性的指导和帮助。方法:北京市4所幼儿园共1 928名儿童,按照《国民体质测定标准手册》(幼儿部分)进行体质测试。随机整群选取了8个班作为整群对照(CG,n=244),并根据体质测试成绩,选取成绩前10%的儿童(TG,n=203)和后10%儿童(BG,n=203),采用Test of Gross Motor Development-3(TGMD-3)对儿童粗大动作发展进行评估,对移动类和球类技能两大类基本动作的动作技能进行评估。结果:1)男童移动动作分值与女童无明显差别;2)男童球类动作技能好于女童,且随年龄增加其优势更加明显;3)体质测试成绩差的儿童,动作发展低于整体水平,特别是其球类动作技能的发展;4)随着年龄的增长,儿童动作发展的差距随年龄增长有逐渐扩大的趋势;5)粗大动作发展与体质测试结果中等相关。结论:针对3~6岁儿童,促进其体质发展,必须重视儿童动作技能的发展,对动作技能发展滞后的儿童应在教学活动中给予更多关注和指导。
