The multi-robot coordinated lifting system is an unconstrained system with a rigid and flexible coupling.The deformation of the flexible rope causes errors in the movement trajectory of the lifting system.Based on the...The multi-robot coordinated lifting system is an unconstrained system with a rigid and flexible coupling.The deformation of the flexible rope causes errors in the movement trajectory of the lifting system.Based on the kinematic and dynamic analysis of the lifting system,the elastic catenary mod-el considering the elasticity and mass of the flexible rope is established,and the effect of the deform-ation of the flexible rope on the position and posture of the suspended object is analyzed.According to the deformation of flexible rope,a real-time trajectory compensation method is proposed based on the compensation principle of position and posture.Under the lifting task of the low-speed move-ment,this is compared with that of the system which neglects the deformation of the flexible rope.The trajectoy of the lifting system considering the deformation of flexible rope.The results show that the mass and elasticity of the flexible rope can not be neglected.Meanwhile,the proposed trajectory compensation method can improve the movement accuracy of the lifting system,which verifies the ef-fectiveness of this compensation method.The research results provide the basis for trajectory plan-ning and coordinated control of the lifting system。展开更多
An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to ...An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to meet the challenge that installing deepwater risers from an S-lay barge is difficult and has not been achieved.The purpose of this paper was to investigate the model test on such an innovative system,which has to be done before field application.By applying the similarity theory,the movement of the S-lay barge is simulated through a six degrees-of-freedom motion platform,and a truncated model riser is utilized for the model testing.The displacement and force boundary conditions at the truncated position of the riser are obtained from the catenary governing equation and become realized by a slideway cart and a loading system designed to control the configuration of the model riser,which presents a similar configuration to a real riser in deepwater.The test results are in very good agreement with theoretical calculations,showing that the active truncated test is applicable for controlling the configuration of the deepwater riser in model testing investigation.展开更多
In lifting sub-system of deep-sea mining system, spherical joint is used to connect lifting pipes to replace fixed joint. Based on Dynamics of Flexible Multi-body systems, the mechanics model of articulated lifting sy...In lifting sub-system of deep-sea mining system, spherical joint is used to connect lifting pipes to replace fixed joint. Based on Dynamics of Flexible Multi-body systems, the mechanics model of articulated lifting system is established. Under the four-grade and six-grade oceanic condition, dynamic responses of lifting system are simulated and experiment verified. The simulation results are consistent with experimental ones. The maximum moment of flexion is 322 kN-m on the first pipe under six-grade sea condition. It is seen that the articulated connection can reduce the moment of flexion. The bending deformation of pipe center is researched, and the maximum is 0. 000479 m on the first pipe. Deformation has a little effect on the motion of system. It is feasible to analyze articulated lifting system by applying the theory of flexible multi-body dynamics. The articulated lifting system is obviously better than the fixed one.展开更多
The underwater installation of marine equipment in deep-water development requires safe lifting and accurate positioning. The heave compensation system is an important technology to ensure normal operation and improve...The underwater installation of marine equipment in deep-water development requires safe lifting and accurate positioning. The heave compensation system is an important technology to ensure normal operation and improve work accuracy. To provide a theoretical basis for the heave compensation system, in this paper, the continuous modeling method is employed to build up a coupled model of deep-water lifting systems in vertical direction. The response characteristics of dynamic movement are investigated. The simulation results show that the resonance problem appears in the process of the whole releasing load, the lifting system generates resonance and the displacement response of the lifting load is maximal when the sinking depth is about 2000 m. This paper also analyzes the main influencing factors on the dynamic response of load including cable stiffness, damping coefficient of the lifting system, mass and added mass of lifting load, among which cable stiffness and damping coefficient of the lifting system have the greatest influence on dynamic response of lifting load when installation load is determined. So the vertical dynamic movement response of the load is reduced by installing a damper on the lifting cable and selecting the appropriate cable stiffness.展开更多
This paper presented a design of an automatic lifting system. It is used for large load powered support and improves the old method wherein powered support lifting depends on manual control. This system applies a high...This paper presented a design of an automatic lifting system. It is used for large load powered support and improves the old method wherein powered support lifting depends on manual control. This system applies a high accuracy gear shunt motor to match the flow for 4 lifting cylinders, and also allocates bypass throttles to realize automatic lifting. Through the dis- placement sensor feedback the height deviation among 4 lifting cylinders during the whole lifting process, when the deviation is up to the sitting value, the corresponding bypass throttle is operated immediately to reduce the deviation, so that the moving platform of the powered support would not be stuck. Through real application, it is shown that this system can realize automatic lifting of powered support; the lifting speed is controlled between 5 and 10 mm/s, and the final aligning accuracy is up to 1 mm.展开更多
In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are e...In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.展开更多
With the arrival of the big data era, the modern higher education model has undergone radical changes, and higher requirements have been put forward for the data literacy of college teachers. The paper first analyzes ...With the arrival of the big data era, the modern higher education model has undergone radical changes, and higher requirements have been put forward for the data literacy of college teachers. The paper first analyzes the connotation of teacher data literacy, and then combs through the status quo and dilemmas of teachers’ data literacy ability in applied universities. The paper proposes to enhance the data literacy ability of teachers from the perspective of organizational learning. Through building a digital culture, building a data-driven teaching environment, and constructing an interdisciplinary learning community to further promote the application of the theory and practice of datafication inside and outside the organization, and ultimately improve the quality of teaching.展开更多
The experiment system of 1000 m deep sea mining system is built up with the similarity theory. Sine mechanism is used to simulate mining ship to generate lateral shock excitation by ocean wave. Simulation and experime...The experiment system of 1000 m deep sea mining system is built up with the similarity theory. Sine mechanism is used to simulate mining ship to generate lateral shock excitation by ocean wave. Simulation and experiment of spherical joint connecting deep sea mining system has been done in band six marine conditions. The results indicate that the moment of spherical joint connecting deep sea mining is smaller than that of the thread connected ones, the lifting pipe of sphelical joint is ＂flexible pipe＂. The flexural torque of the articulated lifting pipe system in pump and buffer is generally periodic variation with some irregularity, the value is stable on 60 N·S, and it is obviously smaller than that of the fixed lifting pipe system; The total displacement exhibits cyclic variation pattern, and the periodicity of them is longer than that of sea current. The results of experiment and simulation are basically consistent. And the analysis in the paper offers theoretical foundation of 1000 m deep sea mining system in China.展开更多
The dynamics of the gravitational lifting system of the deep sea mining industry is demonstrated in this article.A simplified dynamic model is obtained when gravity,buoyancy and drag force are the major concerns.By qu...The dynamics of the gravitational lifting system of the deep sea mining industry is demonstrated in this article.A simplified dynamic model is obtained when gravity,buoyancy and drag force are the major concerns.By quantitative analysis,different variables like bucket size,distribution distance,and filling rate are considered to measure their influence on lifting speed and production rate,which ends up with that the most influential factor is the bucket size,and it has a positive correlation with both the two targets:lifting speed and production rate.Due to the breaking strength of the cable wire rope,a feasible design of such a lifting system should take the tension force into consideration.Hence,the feasibility is also examined and a conclusion is summarized that a combination of the bucket size and the distribution distance should be optimized according to the concrete working conditions.展开更多
The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjud...The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjudgement of the design. Two conditions required by using the lifting technique are presented based on the basic formulae of the lifting. It is pointed out that only the H∞disturbance attenuation problem with no weighting functions can meet these conditions, hence, the application of the lifting technique is quite limited.展开更多
The purpose of this systematic review was to identify the effects of weight-lifting or resistance exercise on breast cancer-related lymphedema.Published articles written in English were retrieved from electronic datab...The purpose of this systematic review was to identify the effects of weight-lifting or resistance exercise on breast cancer-related lymphedema.Published articles written in English were retrieved from electronic databases,including ScienceDirect,PubMed,Scopus,and CINAHL databases.Hand-searches for unpublished papers were also completed.Content analysis was used to examine articles that met the inclusion criteria.Among 525 searched papers,15 papers met the inclusion criteria:13 trials evaluated weight-lifting or resistance exercise alone and two trials evaluated weight-lifting or resistance exercise plus aerobic exercise.The results of the review showed that no arm volume change was observed for either exercise modality.In addition,six included studies showed that weight-lifting or resistance exercise did not cause lymphedema or adverse events in patients at risk of breast cancer-related lymphedema.For patients with breast cancer-related lymphedema,six studies reported that change of swelling outcome measures were not significantly different between the weight-lifting or resistance exercise group and the control group.However,three included studies reported that volume of arm was significantly more reduced in the weight-lifting or resistance exercise group than those in the control group.The findings suggest that supervised resistance exercise may be safe,feasible,and beneficial in patients with breast cancer-related lymphedema or at risk for breast cancer-related lymphedema.However,the limitation of small sample size implies that further research is needed to confirm these findings.展开更多
A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread （ based on API standard） is used and foreign experience in connector design is referred to. With this kind of connec...A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread （ based on API standard） is used and foreign experience in connector design is referred to. With this kind of connector, the lifting pipe wiU only bear the axial force, free of moment. The strength of the connector is analyzed in detail, including the connecting strength of the buttress thread, the dynamic load of the pipe system, pressures inside and outside of the pipe, the lateral stress of the pipe wall and so on. Especially, a geometric model is built for 3-D contact stress analysis. The distribution graph of contact stress is presented. It is indicated that the strength of the spherical connector meets the demand.展开更多
With the increase of bridge reconstruction schemes, synchronous lifting of a bridge is more and more widely used. In order to solve the problems associated with the synchronoas lifting of a bridge, a multi-cylinder sy...With the increase of bridge reconstruction schemes, synchronous lifting of a bridge is more and more widely used. In order to solve the problems associated with the synchronoas lifting of a bridge, a multi-cylinder synchronous lifting power and monitoring system has been developed. This is a distributed control system, which is com- posed of an industrial computer workstation, a programmable logical controller and a hydraulic control system. The system can achieve distributed control and centralized operation of actuators, and centralized management of infor- mation. It not only can implement multi-cylinder synchronous lifting with an unbalanced load, but also can moni- tor the pressure, displacement and stress at each lifting point. The performance of the multi-cylinder synchronous system is verified through its application to several bridge lifting engineering projects. The details of such a project are given.展开更多
In order to achieve a wheelchair lift function, this paper designs a tri-scissors mechanism. Through the so-called H-type transmission and L-type swing rod, the three scissors mechanisms lift in the same rate with onl...In order to achieve a wheelchair lift function, this paper designs a tri-scissors mechanism. Through the so-called H-type transmission and L-type swing rod, the three scissors mechanisms lift in the same rate with only one liner motor while ensuring the stability of the lift. Finite element analysis in ANSYS is performed to verify the material strength. The control system with Sunplus SCM achieves the voice control of wheelchair walking and lifting.展开更多
Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In...Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In this study,assuming representative work environment parameters,pipeline lifting operations are investigated numerically.More specifically,a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights.The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship.The impact of waves on the pipeline is limited,however lifting operations under strong wind and waves should be avoided as far as possible.展开更多
This paper uses the commutant lifting theorem for representations of the nest algebra to deal with the optimal control of infinite dimensional linear time- varying systems. We solve the model matching problem and a ce...This paper uses the commutant lifting theorem for representations of the nest algebra to deal with the optimal control of infinite dimensional linear time- varying systems. We solve the model matching problem and a certain optimal feedback control problem, each of which corresponds with one type of four-block problem. We also obtain a new formula for the optimal performance and prove the existence of an optimal controller.展开更多
The kinetic model of the four-post-frame lifting mechanical system was established. The stiffness and damping matrices of differential equations of motion were obtained by using Lagrange’s equations. And the dynamic ...The kinetic model of the four-post-frame lifting mechanical system was established. The stiffness and damping matrices of differential equations of motion were obtained by using Lagrange’s equations. And the dynamic characteristics of system were analyzed by modal analysis method. Based upon this, the modifications of structural parameters which can improve dynamic performance were discussed. The low-level high-speed palletizer MDJ1200L was taken as a real case in the paper.展开更多
Deficiencies of the performance-based iterative learning control （ILC） for the non-regular systems are investigated in detail, then a faster control input updating and lifting technique is introduced in the design o...Deficiencies of the performance-based iterative learning control （ILC） for the non-regular systems are investigated in detail, then a faster control input updating and lifting technique is introduced in the design of performance index based ILCs for the partial non-regular systems. Two ldnds of optimal ILCs based on different performance indices are considered. Finally, simulation examples are given to illustrate the feasibility of the proposed learning controls.展开更多
Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic...Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic microchannels.Herein,we fabricate those bionic microchannels with various cross-sections by employing projection micro-stereolithography(PμSL)based 3D printing technique.The circumradius of bionic microchannels(pentagonal,square,triangle,and five-pointed star)can be as small as 100μm with precisely fabricated sharp corners.What's more,those bionic microchannels demonstrate marvelous microfluidic performance with strong precursor effects enabled by their sharp corners.Most significantly,those special properties of our bionic microchannels enable them outstanding step lifting performance to transport water to tens of millimeters,though the water can only be transported to at most 20 mm for a single bionic microchannel.The mimicked transpiration based on the step lifting of water from bionic microchannels is also achieved.Those precisely fabricated,low-cost,various cross-sectional bionic microchannels promise applications as microfluidic chips,long-distance unpowered water transportation,step lifting,mimicked transpiration,and so on.展开更多
基金the National Natural Science Foundation of China(No.51965032)the Natural Science Foundation of Gansu Province of China(No.22JR5RA319)+1 种基金the Science and Technology Foundation of Gansu Province of China(No.21YF5WA060)the Excellent Doctoral Student Foundation of Gansu Province of China(No.23JRRA842).
文摘The multi-robot coordinated lifting system is an unconstrained system with a rigid and flexible coupling.The deformation of the flexible rope causes errors in the movement trajectory of the lifting system.Based on the kinematic and dynamic analysis of the lifting system,the elastic catenary mod-el considering the elasticity and mass of the flexible rope is established,and the effect of the deform-ation of the flexible rope on the position and posture of the suspended object is analyzed.According to the deformation of flexible rope,a real-time trajectory compensation method is proposed based on the compensation principle of position and posture.Under the lifting task of the low-speed move-ment,this is compared with that of the system which neglects the deformation of the flexible rope.The trajectoy of the lifting system considering the deformation of flexible rope.The results show that the mass and elasticity of the flexible rope can not be neglected.Meanwhile,the proposed trajectory compensation method can improve the movement accuracy of the lifting system,which verifies the ef-fectiveness of this compensation method.The research results provide the basis for trajectory plan-ning and coordinated control of the lifting system。
基金support from the National Natural Science Foundation of China (granted number 50979113)the National 863 Program of China (granted number 2006AA09A105)
文摘An S-lay crane barge,named CNOOC 201,has been built for pipe laying in deepwater oil/gas fields in the South China Sea.It is due to be commissioned by the end of the year 2010.A special lifting system is developed to meet the challenge that installing deepwater risers from an S-lay barge is difficult and has not been achieved.The purpose of this paper was to investigate the model test on such an innovative system,which has to be done before field application.By applying the similarity theory,the movement of the S-lay barge is simulated through a six degrees-of-freedom motion platform,and a truncated model riser is utilized for the model testing.The displacement and force boundary conditions at the truncated position of the riser are obtained from the catenary governing equation and become realized by a slideway cart and a loading system designed to control the configuration of the model riser,which presents a similar configuration to a real riser in deepwater.The test results are in very good agreement with theoretical calculations,showing that the active truncated test is applicable for controlling the configuration of the deepwater riser in model testing investigation.
基金This research project was financially supported by China Ocean Mineral Resources R&D Association(Grant No.DY105-03-02-17)Ph.D.Programs Foundation of Ministry of Education of China(Grant No.20060008025)
文摘In lifting sub-system of deep-sea mining system, spherical joint is used to connect lifting pipes to replace fixed joint. Based on Dynamics of Flexible Multi-body systems, the mechanics model of articulated lifting system is established. Under the four-grade and six-grade oceanic condition, dynamic responses of lifting system are simulated and experiment verified. The simulation results are consistent with experimental ones. The maximum moment of flexion is 322 kN-m on the first pipe under six-grade sea condition. It is seen that the articulated connection can reduce the moment of flexion. The bending deformation of pipe center is researched, and the maximum is 0. 000479 m on the first pipe. Deformation has a little effect on the motion of system. It is feasible to analyze articulated lifting system by applying the theory of flexible multi-body dynamics. The articulated lifting system is obviously better than the fixed one.
基金sponsored by the Major Projects of National Science and Technology (2011ZX05056-003)
文摘The underwater installation of marine equipment in deep-water development requires safe lifting and accurate positioning. The heave compensation system is an important technology to ensure normal operation and improve work accuracy. To provide a theoretical basis for the heave compensation system, in this paper, the continuous modeling method is employed to build up a coupled model of deep-water lifting systems in vertical direction. The response characteristics of dynamic movement are investigated. The simulation results show that the resonance problem appears in the process of the whole releasing load, the lifting system generates resonance and the displacement response of the lifting load is maximal when the sinking depth is about 2000 m. This paper also analyzes the main influencing factors on the dynamic response of load including cable stiffness, damping coefficient of the lifting system, mass and added mass of lifting load, among which cable stiffness and damping coefficient of the lifting system have the greatest influence on dynamic response of lifting load when installation load is determined. So the vertical dynamic movement response of the load is reduced by installing a damper on the lifting cable and selecting the appropriate cable stiffness.
文摘This paper presented a design of an automatic lifting system. It is used for large load powered support and improves the old method wherein powered support lifting depends on manual control. This system applies a high accuracy gear shunt motor to match the flow for 4 lifting cylinders, and also allocates bypass throttles to realize automatic lifting. Through the dis- placement sensor feedback the height deviation among 4 lifting cylinders during the whole lifting process, when the deviation is up to the sitting value, the corresponding bypass throttle is operated immediately to reduce the deviation, so that the moving platform of the powered support would not be stuck. Through real application, it is shown that this system can realize automatic lifting of powered support; the lifting speed is controlled between 5 and 10 mm/s, and the final aligning accuracy is up to 1 mm.
基金Ho Chi Minh City University of Technology(HCMUT)Vietnam National University Ho Chi Minh City(VNU-HCM)for supporting this study。
文摘In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.
文摘With the arrival of the big data era, the modern higher education model has undergone radical changes, and higher requirements have been put forward for the data literacy of college teachers. The paper first analyzes the connotation of teacher data literacy, and then combs through the status quo and dilemmas of teachers’ data literacy ability in applied universities. The paper proposes to enhance the data literacy ability of teachers from the perspective of organizational learning. Through building a digital culture, building a data-driven teaching environment, and constructing an interdisciplinary learning community to further promote the application of the theory and practice of datafication inside and outside the organization, and ultimately improve the quality of teaching.
基金This research was financially supported by China Ocean Mineral Resources Reasearch and Design Association (GrantNo DY105-03-02-17)Ph.D Programs Foundation of Ministry of Education of China (Grant No20060008025)
文摘The experiment system of 1000 m deep sea mining system is built up with the similarity theory. Sine mechanism is used to simulate mining ship to generate lateral shock excitation by ocean wave. Simulation and experiment of spherical joint connecting deep sea mining system has been done in band six marine conditions. The results indicate that the moment of spherical joint connecting deep sea mining is smaller than that of the thread connected ones, the lifting pipe of sphelical joint is ＂flexible pipe＂. The flexural torque of the articulated lifting pipe system in pump and buffer is generally periodic variation with some irregularity, the value is stable on 60 N·S, and it is obviously smaller than that of the fixed lifting pipe system; The total displacement exhibits cyclic variation pattern, and the periodicity of them is longer than that of sea current. The results of experiment and simulation are basically consistent. And the analysis in the paper offers theoretical foundation of 1000 m deep sea mining system in China.
文摘The dynamics of the gravitational lifting system of the deep sea mining industry is demonstrated in this article.A simplified dynamic model is obtained when gravity,buoyancy and drag force are the major concerns.By quantitative analysis,different variables like bucket size,distribution distance,and filling rate are considered to measure their influence on lifting speed and production rate,which ends up with that the most influential factor is the bucket size,and it has a positive correlation with both the two targets:lifting speed and production rate.Due to the breaking strength of the cable wire rope,a feasible design of such a lifting system should take the tension force into consideration.Hence,the feasibility is also examined and a conclusion is summarized that a combination of the bucket size and the distribution distance should be optimized according to the concrete working conditions.
基金Supported by the Harbin Engineering University Fund for Basic Projects (heuft06041)
文摘The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjudgement of the design. Two conditions required by using the lifting technique are presented based on the basic formulae of the lifting. It is pointed out that only the H∞disturbance attenuation problem with no weighting functions can meet these conditions, hence, the application of the lifting technique is quite limited.
文摘The purpose of this systematic review was to identify the effects of weight-lifting or resistance exercise on breast cancer-related lymphedema.Published articles written in English were retrieved from electronic databases,including ScienceDirect,PubMed,Scopus,and CINAHL databases.Hand-searches for unpublished papers were also completed.Content analysis was used to examine articles that met the inclusion criteria.Among 525 searched papers,15 papers met the inclusion criteria:13 trials evaluated weight-lifting or resistance exercise alone and two trials evaluated weight-lifting or resistance exercise plus aerobic exercise.The results of the review showed that no arm volume change was observed for either exercise modality.In addition,six included studies showed that weight-lifting or resistance exercise did not cause lymphedema or adverse events in patients at risk of breast cancer-related lymphedema.For patients with breast cancer-related lymphedema,six studies reported that change of swelling outcome measures were not significantly different between the weight-lifting or resistance exercise group and the control group.However,three included studies reported that volume of arm was significantly more reduced in the weight-lifting or resistance exercise group than those in the control group.The findings suggest that supervised resistance exercise may be safe,feasible,and beneficial in patients with breast cancer-related lymphedema or at risk for breast cancer-related lymphedema.However,the limitation of small sample size implies that further research is needed to confirm these findings.
基金This research was financially supported by China Ocean Mineral Resources R &D Association (Grant No. DY105-03-02-17) .
文摘A flexible connector of lifting pipes in a deep sea mining system is designed. The buttress thread （ based on API standard） is used and foreign experience in connector design is referred to. With this kind of connector, the lifting pipe wiU only bear the axial force, free of moment. The strength of the connector is analyzed in detail, including the connecting strength of the buttress thread, the dynamic load of the pipe system, pressures inside and outside of the pipe, the lateral stress of the pipe wall and so on. Especially, a geometric model is built for 3-D contact stress analysis. The distribution graph of contact stress is presented. It is indicated that the strength of the spherical connector meets the demand.
基金supported by the Ph.D. Programs Foundation of Ministry of Education of China under Grant No. 20070056010Tianjin Municipal Natural Science Foundation under Grant No.07JCZBJC09900Tianjin key technology research for majorproject under Contract No.05ZHGCGX00500
文摘With the increase of bridge reconstruction schemes, synchronous lifting of a bridge is more and more widely used. In order to solve the problems associated with the synchronoas lifting of a bridge, a multi-cylinder synchronous lifting power and monitoring system has been developed. This is a distributed control system, which is com- posed of an industrial computer workstation, a programmable logical controller and a hydraulic control system. The system can achieve distributed control and centralized operation of actuators, and centralized management of infor- mation. It not only can implement multi-cylinder synchronous lifting with an unbalanced load, but also can moni- tor the pressure, displacement and stress at each lifting point. The performance of the multi-cylinder synchronous system is verified through its application to several bridge lifting engineering projects. The details of such a project are given.
基金Supported by Special Topic of the Ministry of Education about Humanities and Social Sciences(12JDGC007)ZheJiang Henglin Chair Industry Co.,Ltd.-Hefei University of Technology Green Seat and Intelligent House Innovate Team
文摘In order to achieve a wheelchair lift function, this paper designs a tri-scissors mechanism. Through the so-called H-type transmission and L-type swing rod, the three scissors mechanisms lift in the same rate with only one liner motor while ensuring the stability of the lift. Finite element analysis in ANSYS is performed to verify the material strength. The control system with Sunplus SCM achieves the voice control of wheelchair walking and lifting.
基金This study was financially supported by the Program for Scientific Research Start-Up Funds of Guangdong Ocean University(060302072101)Comparative Study,and Optimization of Horizontal Lifting of Subsea Pipeline(2021E05011).
文摘Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In this study,assuming representative work environment parameters,pipeline lifting operations are investigated numerically.More specifically,a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights.The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship.The impact of waves on the pipeline is limited,however lifting operations under strong wind and waves should be avoided as far as possible.
文摘This paper uses the commutant lifting theorem for representations of the nest algebra to deal with the optimal control of infinite dimensional linear time- varying systems. We solve the model matching problem and a certain optimal feedback control problem, each of which corresponds with one type of four-block problem. We also obtain a new formula for the optimal performance and prove the existence of an optimal controller.
文摘The kinetic model of the four-post-frame lifting mechanical system was established. The stiffness and damping matrices of differential equations of motion were obtained by using Lagrange’s equations. And the dynamic characteristics of system were analyzed by modal analysis method. Based upon this, the modifications of structural parameters which can improve dynamic performance were discussed. The low-level high-speed palletizer MDJ1200L was taken as a real case in the paper.
基金supported by the National Natural Science Foundation of China (No.60774023)Hunan Provincial Natural Science Foundation (No.06JJ50141)
文摘Deficiencies of the performance-based iterative learning control （ILC） for the non-regular systems are investigated in detail, then a faster control input updating and lifting technique is introduced in the design of performance index based ILCs for the partial non-regular systems. Two ldnds of optimal ILCs based on different performance indices are considered. Finally, simulation examples are given to illustrate the feasibility of the proposed learning controls.
基金supported by the National Natural Science Foundation of China(52006056)the Experiments for Space Exploration Program and the Qian Xuesen Laboratory,China Academy of Space Technology(TKTSPY-2020-01-04)+2 种基金the Key-Area Research and Development Program of Guangdong Province(2020B090923003)partly supported by Natural Science Foundation of Hunan through Grant No.2020JJ3012Natural Research Institute for Family Planning。
文摘Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic microchannels.Herein,we fabricate those bionic microchannels with various cross-sections by employing projection micro-stereolithography(PμSL)based 3D printing technique.The circumradius of bionic microchannels(pentagonal,square,triangle,and five-pointed star)can be as small as 100μm with precisely fabricated sharp corners.What's more,those bionic microchannels demonstrate marvelous microfluidic performance with strong precursor effects enabled by their sharp corners.Most significantly,those special properties of our bionic microchannels enable them outstanding step lifting performance to transport water to tens of millimeters,though the water can only be transported to at most 20 mm for a single bionic microchannel.The mimicked transpiration based on the step lifting of water from bionic microchannels is also achieved.Those precisely fabricated,low-cost,various cross-sectional bionic microchannels promise applications as microfluidic chips,long-distance unpowered water transportation,step lifting,mimicked transpiration,and so on.
