Measuring the internal stress of Al alloy forgings accurately is critical for controlling the deformation during the subsequent machine process.In this work,the crack compliance method was used to calculate the intern...Measuring the internal stress of Al alloy forgings accurately is critical for controlling the deformation during the subsequent machine process.In this work,the crack compliance method was used to calculate the internal residual stress of Al-Cu high strength alloys,and the effect of various model parameters of crack compliance method on the calculated precision was studied by combining the numerical simulation and experimental method.The results show that the precision first increased and then decreased with increasing the crack range.The decreased precision when using a high crack range was due to the strain fluctuation during the machining process,and the optimized crack range was 71%of the thickness of forgings.Low orders of Legendre polynomial can result in residual stress curve more smooth,while high orders led to the occurrence of distortion.The Tikhonov regularization method effectively suppressed the distortion of residual stress caused by the fluctuation of strain data,which significantly improved the precision.In addition,The crack compliance method with optimized parameters was used to measure the residual stress of Al-Cu alloy with different quenching methods.The calculated results demonstrated that the distribution of residual stress was obtained accurately.展开更多
In order to guarantee safety and stability during physical human-robot-interaction(p HRI) in the occasion of service or industrial operation, a serial integrated rotary joint with the characteristics of passive and ac...In order to guarantee safety and stability during physical human-robot-interaction(p HRI) in the occasion of service or industrial operation, a serial integrated rotary joint with the characteristics of passive and active compliance is proposed. Passive compliance is achieved by a designed elastic element, such that the compliant joint may minimize large force which occurs during accidental impacts and, further, may offer more accurate and stable force control and a capacity for energy storage. Meanwhile, the modeling of the compliant joint is comprehensively analyzed, including the effect of the motor model on the overall control system. In order to realize the active compliance, a new method of impedance control is proposed. On the basis of PD control, a more compliant impedance controller is introduced. Experimental results show that the serial integrated rotary joint can provide more effective safety compliance during physical interaction, which has also been well applied in our designed massage robot and rehabilitation robot.展开更多
Discontinuities constitute an integral part of rock mass and inherently affect its anisotropic deformation behavior.This work focuses on the equivalent elastic deformation of rock mass with multiple persistent joint s...Discontinuities constitute an integral part of rock mass and inherently affect its anisotropic deformation behavior.This work focuses on the equivalent elastic deformation of rock mass with multiple persistent joint sets.A new method based on the space geometric and mechanical properties of the modified crack tensor is proposed,providing an analytical solution for the equivalent elastic compliance tensor of rock mass.A series of experiments validate the capability of the compliance tensor to accurately represent the deformation of rock mass with multiple persistent joint sets,based on conditions set by the basic hypothesis.The spatially varying rules of the equivalent elastic parameters of rock mass with a single joint set are analyzed to reveal the universal law of the stratified rock mass.展开更多
In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators wit...In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems,an experimental measurement and analysis method was presented.By measuring the resonant frequency,the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator(TAR)with different lengths.The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest(28.222)with the least dissipation factor of 0.035 4.So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes.Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system.展开更多
The willingness to comply with the law or rule is a litmus test of the quality of legislation.Without compliance,there is no rule of law,no matter how well the laws or regulations are designed.Regulatory compliance co...The willingness to comply with the law or rule is a litmus test of the quality of legislation.Without compliance,there is no rule of law,no matter how well the laws or regulations are designed.Regulatory compliance continues to be one of the greatest challenges for energy industry due to factors such as central protectionism,inadequate legal system and weak law enforcement.To meet the challenges of achieving environmental compliance,it is proposed that the environmental compliance system should incorporate three subsystems:a primary environmental compliance system,a primary environmental compliance system,and an environmental noncompliance response system.展开更多
A nonlinear impact damping model of single-degree-of-freedom spur cylindrical gear with backlash and time-varying stiffness was established. Systematic analyses of the dynamic responses were performed. First, the nonl...A nonlinear impact damping model of single-degree-of-freedom spur cylindrical gear with backlash and time-varying stiffness was established. Systematic analyses of the dynamic responses were performed. First, the nonlinear damping coefficient was considered as a constant parameter with two types of compliance exponent, meanwhile, dynamic factors were adopted to depict the dynamic characteristics. Second, the bifurcation graphs were plotted, where the damping coefficient was obtained along with the impact velocity and coefficient of restitution. The results show that light and heavy load conditions have an effect on the responses when the compliance exponent is integer. On the contrary, when the compliance exponent is non-integer, the dynamic responses are slightly affected, namely the system is more stable than the former situation.展开更多
A reliability-based stochastic system optimum congestion pricing(SSOCP) model with endogenous market penetration and compliance rate in an advanced traveler information systems(ATIS) environment was proposed. All trav...A reliability-based stochastic system optimum congestion pricing(SSOCP) model with endogenous market penetration and compliance rate in an advanced traveler information systems(ATIS) environment was proposed. All travelers were divided into two classes. The first guided travelers were referred to as the equipped travelers who follow ATIS advice, while the second unguided travelers were referred to as the unequipped travelers and the equipped travelers who do not follow the ATIS advice(also referred to as non-complied travelers). Travelers were assumed to take travel time, congestion pricing, and travel time reliability into account when making travel route choice decisions. In order to arrive at on time, travelers needed to allow for a safety margin to their trip.The market penetration of ATIS was determined by a continuous increasing function of the information benefit, and the ATIS compliance rate of equipped travelers was given as the probability of the actually experienced travel costs of guided travelers less than or equal to those of unguided travelers. The analysis results could enhance our understanding of the effect of travel demand level and travel time reliability confidence level on the ATIS market penetration and compliance rate; and the effect of travel time perception variation of guided and unguided travelers on the mean travel cost savings(MTCS) of the equipped travelers, the ATIS market penetration, compliance rate, and the total network effective travel time(TNETT).展开更多
1.Introduction Biodegradable polymeric biomaterials have been fabricated into various biomedical implants such as drug delivery nanoparticles,tissue engineering scaffolds and orthopedic devices.Using biodegradable pol...1.Introduction Biodegradable polymeric biomaterials have been fabricated into various biomedical implants such as drug delivery nanoparticles,tissue engineering scaffolds and orthopedic devices.Using biodegradable polymers as implant materials is beneficial as the implants are degraded and cleared by the body once their missions are complete,leaving no foreign materials in the body.Driven by the versatile needs in biomedical engineering,searching for ideal functional biodegradable polymers has been an endless effort in the past decades.Among biodegradable polymers,citrate-based biodegradable elastomeric(CABE)polymers have recently received increasing attention because their compliance under force can closely resemble the elastic展开更多
In order to simulate the gait of human walking on different terrains a new robot with six degrees of freedom was proposed. Based on sand bearing characteristic compliance control was introduced to control system in ho...In order to simulate the gait of human walking on different terrains a new robot with six degrees of freedom was proposed. Based on sand bearing characteristic compliance control was introduced to control system in horizontal and vertical movement directions at the end of the robot,and position control in attitude. With Matlab/Simulink toolbox,the system control models were established,and the bearing characteristics of rigid ground,hard sand,soft sand and softer sand were simulated. The results show that 0,0.62,0.89 and 1.12 mm are the maximal subsidences of the four kinds of ground along the positive direction of x-axis,respectively,and 0,-0.96,-1.99 and -3.00 mm are the maximal subsidences along the negative direction of x-axis,respectively. Every subsidence along y-axis is negative,and 0,-4.12,-8.23 and -12.01 mm are the maximal subsidences of the four kinds of ground,respectively. Simulation results show that the subsidence of footboard points to inferior anterior in early stage of stand phase,while points to posterior aspect in late stage. The subsidence tends to point to posterior aspect in the whole. These results are basically consistent with the gait characteristics of human walking on sand. Gait simulation of the robot for human walking on sand is achieved.展开更多
In the applications of joint control and robot movement,the joint torque estimation has been treated as an effective technique and widely used.Researches are made to analyze the kinematic and compliance model of the r...In the applications of joint control and robot movement,the joint torque estimation has been treated as an effective technique and widely used.Researches are made to analyze the kinematic and compliance model of the robot joint with harmonic drive to acquire high precision torque output.Through analyzing the structures of the harmonic drive and experiment apparatus,a scheme of the proposed joint torque estimation method based on both the dynamic characteristics and unscented Kalman filter(UKF)is designed and built.Based on research and scheme,torque estimation methods in view of only harmonic drive compliance model and compliance model with the Kalman filter are simulated as guidance and reference to promote the research on the torque estimation technique.Finally,a promoted torque estimation method depending on both harmonic drive compliance model and UKF is designed,and simulation results compared with the measurements of a commercial torque sensor,have verified the effectiveness of the proposed method.展开更多
基金Project(51875583)supported by the National Natural Science Foundation of ChinaProject(zzyjkt2018-03)supported by the State Key Laboratory of High Performance Complex Manufacturing,China。
文摘Measuring the internal stress of Al alloy forgings accurately is critical for controlling the deformation during the subsequent machine process.In this work,the crack compliance method was used to calculate the internal residual stress of Al-Cu high strength alloys,and the effect of various model parameters of crack compliance method on the calculated precision was studied by combining the numerical simulation and experimental method.The results show that the precision first increased and then decreased with increasing the crack range.The decreased precision when using a high crack range was due to the strain fluctuation during the machining process,and the optimized crack range was 71%of the thickness of forgings.Low orders of Legendre polynomial can result in residual stress curve more smooth,while high orders led to the occurrence of distortion.The Tikhonov regularization method effectively suppressed the distortion of residual stress caused by the fluctuation of strain data,which significantly improved the precision.In addition,The crack compliance method with optimized parameters was used to measure the residual stress of Al-Cu alloy with different quenching methods.The calculated results demonstrated that the distribution of residual stress was obtained accurately.
基金Project(81473694)supported by the National Natural Science Foundation of ChinaProject(2016A1027)supported by the major Project of Zhongshan City,ChinaProject(2016FZFC007)supported by the Intelligent Equipment and Technology of Automation Research and Development Platform,China
文摘In order to guarantee safety and stability during physical human-robot-interaction(p HRI) in the occasion of service or industrial operation, a serial integrated rotary joint with the characteristics of passive and active compliance is proposed. Passive compliance is achieved by a designed elastic element, such that the compliant joint may minimize large force which occurs during accidental impacts and, further, may offer more accurate and stable force control and a capacity for energy storage. Meanwhile, the modeling of the compliant joint is comprehensively analyzed, including the effect of the motor model on the overall control system. In order to realize the active compliance, a new method of impedance control is proposed. On the basis of PD control, a more compliant impedance controller is introduced. Experimental results show that the serial integrated rotary joint can provide more effective safety compliance during physical interaction, which has also been well applied in our designed massage robot and rehabilitation robot.
基金Projects(41172284,51379202) supported by the National Natural Science Foundation of ChinaProject(2013CB036405) supported by the National Basic Research Program of ChinaProject(2013BAB02B01) supported by the National Key Technologies R&D Program of China
文摘Discontinuities constitute an integral part of rock mass and inherently affect its anisotropic deformation behavior.This work focuses on the equivalent elastic deformation of rock mass with multiple persistent joint sets.A new method based on the space geometric and mechanical properties of the modified crack tensor is proposed,providing an analytical solution for the equivalent elastic compliance tensor of rock mass.A series of experiments validate the capability of the compliance tensor to accurately represent the deformation of rock mass with multiple persistent joint sets,based on conditions set by the basic hypothesis.The spatially varying rules of the equivalent elastic parameters of rock mass with a single joint set are analyzed to reveal the universal law of the stratified rock mass.
基金Projects(50676068,50576024)supported by the National Natural Science Foundation of China
文摘In thermoacoustic system,the characteristic of complex compliance of a regenerator has a great influence on energy stored and dissipation of the whole engine.In order to investigate the performance of regenerators with different matrix geometries and materials coupled with different acoustic systems,an experimental measurement and analysis method was presented.By measuring the resonant frequency,the complex compliance and quality factor of five kinds of matrix were experimentally analyzed respectively in the system of loudspeaker-driven thermoacoustic resonator(TAR)with different lengths.The experimental results show that the real part of complex compliance of the regenerator with pin-array has a maximum value among the measured matrixes and its quality factor is the largest(28.222)with the least dissipation factor of 0.035 4.So the pin-array matrix is testified to behave more excellently on the energy conversion than other matrixes.Compared with other factors the complex compliance of a regenerator contributes more to the performance of a thermoacoustic system.
基金the staged achievement of National Social Science Project(15CFX053)supported by scientific research project of SWPU(2017RW010)funded by the Chinese Scholarship Council and the Energy Law Research Team of SWPU(2018CXTD13)。
文摘The willingness to comply with the law or rule is a litmus test of the quality of legislation.Without compliance,there is no rule of law,no matter how well the laws or regulations are designed.Regulatory compliance continues to be one of the greatest challenges for energy industry due to factors such as central protectionism,inadequate legal system and weak law enforcement.To meet the challenges of achieving environmental compliance,it is proposed that the environmental compliance system should incorporate three subsystems:a primary environmental compliance system,a primary environmental compliance system,and an environmental noncompliance response system.
基金Project(51275530)supported by the National Natural Science Foundation of ChinaProject(2011CB706800)supported by the National Basic Research Program of ChinaProject(2013zzts198)supported by the Fundamental Research Founds of Central South University,China
文摘A nonlinear impact damping model of single-degree-of-freedom spur cylindrical gear with backlash and time-varying stiffness was established. Systematic analyses of the dynamic responses were performed. First, the nonlinear damping coefficient was considered as a constant parameter with two types of compliance exponent, meanwhile, dynamic factors were adopted to depict the dynamic characteristics. Second, the bifurcation graphs were plotted, where the damping coefficient was obtained along with the impact velocity and coefficient of restitution. The results show that light and heavy load conditions have an effect on the responses when the compliance exponent is integer. On the contrary, when the compliance exponent is non-integer, the dynamic responses are slightly affected, namely the system is more stable than the former situation.
基金Project(12YJCZH309) supported by Humanities and Social Sciences Youth Foundation of the Ministry of Education of ChinaProject(20120041120006) supported by Specialized Research Fund for the Doctoral Program of Higher Education,China
文摘A reliability-based stochastic system optimum congestion pricing(SSOCP) model with endogenous market penetration and compliance rate in an advanced traveler information systems(ATIS) environment was proposed. All travelers were divided into two classes. The first guided travelers were referred to as the equipped travelers who follow ATIS advice, while the second unguided travelers were referred to as the unequipped travelers and the equipped travelers who do not follow the ATIS advice(also referred to as non-complied travelers). Travelers were assumed to take travel time, congestion pricing, and travel time reliability into account when making travel route choice decisions. In order to arrive at on time, travelers needed to allow for a safety margin to their trip.The market penetration of ATIS was determined by a continuous increasing function of the information benefit, and the ATIS compliance rate of equipped travelers was given as the probability of the actually experienced travel costs of guided travelers less than or equal to those of unguided travelers. The analysis results could enhance our understanding of the effect of travel demand level and travel time reliability confidence level on the ATIS market penetration and compliance rate; and the effect of travel time perception variation of guided and unguided travelers on the mean travel cost savings(MTCS) of the equipped travelers, the ATIS market penetration, compliance rate, and the total network effective travel time(TNETT).
基金supported in part by a NSF CAREER award(1313553)a NIH R01 award (EB012575)+2 种基金a NSF collaborative research award(1266116)a CPRIT High Impact/High Risk Research Award(RP110412)a research award from National Natural Sciences Foundation of China(31228007)
文摘1.Introduction Biodegradable polymeric biomaterials have been fabricated into various biomedical implants such as drug delivery nanoparticles,tissue engineering scaffolds and orthopedic devices.Using biodegradable polymers as implant materials is beneficial as the implants are degraded and cleared by the body once their missions are complete,leaving no foreign materials in the body.Driven by the versatile needs in biomedical engineering,searching for ideal functional biodegradable polymers has been an endless effort in the past decades.Among biodegradable polymers,citrate-based biodegradable elastomeric(CABE)polymers have recently received increasing attention because their compliance under force can closely resemble the elastic
基金Project(60575053) supported by the National Natural Science Foundation of China
文摘In order to simulate the gait of human walking on different terrains a new robot with six degrees of freedom was proposed. Based on sand bearing characteristic compliance control was introduced to control system in horizontal and vertical movement directions at the end of the robot,and position control in attitude. With Matlab/Simulink toolbox,the system control models were established,and the bearing characteristics of rigid ground,hard sand,soft sand and softer sand were simulated. The results show that 0,0.62,0.89 and 1.12 mm are the maximal subsidences of the four kinds of ground along the positive direction of x-axis,respectively,and 0,-0.96,-1.99 and -3.00 mm are the maximal subsidences along the negative direction of x-axis,respectively. Every subsidence along y-axis is negative,and 0,-4.12,-8.23 and -12.01 mm are the maximal subsidences of the four kinds of ground,respectively. Simulation results show that the subsidence of footboard points to inferior anterior in early stage of stand phase,while points to posterior aspect in late stage. The subsidence tends to point to posterior aspect in the whole. These results are basically consistent with the gait characteristics of human walking on sand. Gait simulation of the robot for human walking on sand is achieved.
基金supported by the National Natural Science Foundation of China(51879055)。
文摘In the applications of joint control and robot movement,the joint torque estimation has been treated as an effective technique and widely used.Researches are made to analyze the kinematic and compliance model of the robot joint with harmonic drive to acquire high precision torque output.Through analyzing the structures of the harmonic drive and experiment apparatus,a scheme of the proposed joint torque estimation method based on both the dynamic characteristics and unscented Kalman filter(UKF)is designed and built.Based on research and scheme,torque estimation methods in view of only harmonic drive compliance model and compliance model with the Kalman filter are simulated as guidance and reference to promote the research on the torque estimation technique.Finally,a promoted torque estimation method depending on both harmonic drive compliance model and UKF is designed,and simulation results compared with the measurements of a commercial torque sensor,have verified the effectiveness of the proposed method.
