A novel weft insertion mechanism named eccentric conjugate non-circular gear & crank-rocker & gears train weft insertion mechanism was proposed in order to better meet the requirements of rapier loom's wef...A novel weft insertion mechanism named eccentric conjugate non-circular gear & crank-rocker & gears train weft insertion mechanism was proposed in order to better meet the requirements of rapier loom's weft insertion mechanism as well as reduce the manufacturing difficulty. Meanwhile, based on the working principle of this mechanism, kinematical mathematic models of this mechanism were established and an aided analysis and simulation software was compiled. The influences of eccentricity ratio, deformation coefficient, and other important parameters on the kinematics characteristics of this mechanism were analyzed by using the software. A group of preferable parameters which could meet the requirements of weft insertion technology were obtained by means of human-computer interactive optimization method. The maximum velocity, maximum acceleration, and variation of acceleration of this mechanism are smaller than those of the conjugate cam weft insertion mechanism applied on TT96 rapier loom under the conditions of the same unilateral total stroke of rapier head and the same rotary speed of loom spindle; meanwhile the other demands of weaving technology can be met by this novel weft insertion mechanism.展开更多
In order to analyze the kinematic performances of elliptic-gear and crank-rocker(EGCR) beating-up mechanism, kinematic mathematic models of the mechanism were established, and an aided analysis and simulation software...In order to analyze the kinematic performances of elliptic-gear and crank-rocker(EGCR) beating-up mechanism, kinematic mathematic models of the mechanism were established, and an aided analysis and simulation software were compiled. This software can display the kinematic characteristics and simulation motion of the mechanism according to different parameters. It also supplies a platform for human-computer interaction. A group of satisfactory parameters were selected by the software. A test bed of EGCR beating-up mechanism was developed according to these parameters. The kinematic performances of the mechanism were verified by high-speed video tape recorder.展开更多
Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic bou...Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic boundary and contact problems in simulation are solved. Transient stress distribution of contact area, transient strain distribution of nodes in typical section and strain distribution of the workpiece at last are attained, the place and the cause of crack are analyzed. Strain variation curves with time of offset spinning and conventional spinning are compared. It shows the mechanism difference between offset spinning and conventional spinning. In addition, simulation results show how strain distribution of typical section, thickness of some typical nodes, axial extension in left section and force of three rollers change with time. According to the study of the variation curve, material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The simulation results discover that offset distance is the key to manufacture offset non-symmetric tube, and process parameters change with spinning angle. Experiment data really reflect different process parameters' influence on conventional symmetric and offset spinning force. Experiments accord well with simulation.展开更多
According to the revised Cailikefu's rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus success...According to the revised Cailikefu's rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus successfully established for 2 800 mm heavy shear of some iron and steel company. Shear and bar forces of steel plate, before and after the adoption of negative offset structure, were analyzed, as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. It was found that the back-wall push force keeps large even at the time that the maximum rolling shear was obtained; meanwhile, back-wall push force is the most approximate to side forces when 60--100 mm of offset was adopted. Both theoretical results and onsite shear quality show that the negative offset plays an important role in ensuring the stability of pure rolling shear and keeping blade clearance constant.展开更多
According to revised Cailikefu’s rolling shear force formula,motion path equation of spatial seven-bar path is built,and mechanical model,with such new structural features as negative offset,is thus successfully esta...According to revised Cailikefu’s rolling shear force formula,motion path equation of spatial seven-bar path is built,and mechanical model,with such new structural features as negative offset,is thus successfully established for 2 800 mm heavy shear of some Iron&Steel Company. Shear force and bar force of steel plate,before and after adoption of negative offset structure,are analyzed,as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. The discovery is that back-wall push force could be kept large enough at rolling start-up (i.e. the time that the maximum rolling shear produces),meanwhile,back-wall push force is the most approximate to side forces with adoption of 60 mm-100 mm offset. Theoretical results and on-site shear quality both indicate that new structural features such as negative offset plays an important role in ensuring pure rolling shear and keeping blade clearance constant,which provide an effective means to improve quality of steel plate.展开更多
在电动汽车无线充电系统中,负载锂电池的充电过程为先恒流再恒压,因此,无线电能传输(wireless power transfer,WPT)系统需要同时具备实现双输出的能力,且在双输出状态之间进行平稳切换。基于此,分析双边LCC(inductor-capacitor-capacit...在电动汽车无线充电系统中,负载锂电池的充电过程为先恒流再恒压,因此,无线电能传输(wireless power transfer,WPT)系统需要同时具备实现双输出的能力,且在双输出状态之间进行平稳切换。基于此,分析双边LCC(inductor-capacitor-capacitor)拓扑实现与负载无关的恒流/恒压输出条件,给出参数设计方法。针对系统可能会随机在不同方向上出现位移的情况,采用了双向同轴平面线圈的结构,即原边线圈由内外2个沿相反方向绕制的线圈串联组成。通过仿真和实验验证了本文提出的电动汽车无线充电系统具备同时实现恒流/恒压输出的能力,且在多方向偏移工况下实现稳定输出。展开更多
Forest carbon offset(FCO)projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets.However,there are challenges and barriers to develo...Forest carbon offset(FCO)projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets.However,there are challenges and barriers to developing an FCO project,such as carbon leakage and cost-eff ectiveness.There have been few attempts to summarize and synthesize all types and aspects of existing challenges and possible solutions for FCO projects.This paper systematically reviews and discusses the current challenges involved in developing FCO projects,and then draws on the experience and lessons of existing projects to show how those challenges were addressed in world-leading voluntary carbon standards,namely the Verifi ed Carbon Standard,the American Carbon Registry,the Climate Action Reserve,and Plan Vivo.These voluntary markets have rich experience in FCO projects and are responsible for a signifi cant share of the market.From the 53 publications used in this analysis,three broad thematic categories of challenges emerged.These were related to methodology,socio-economic implications,and implementation.Methodological challenges,particularly additionality,permanence,and leakage,were the focus of 46%of the selected research papers,while socio-economic challenges,including transaction,social,and opportunity costs,were addressed by 35%.The remaining 19%of the research articles focused on implementational challenges related to monitoring,reporting,and verifi cation.Major voluntary standards adequately addressed most of the methodological and implementational barriers by adopting various approaches.However,the standards did not adequately address socio-economic issues,despite these being the second most frequently discussed theme in the papers analyzed.More research is clearly needed on the socio-economic challenges involved in the development of FCO projects.For the development of high-quality forestry carbon off set projects,there are many challenges and no simple,universal recipe for addressing them.However,it is crucial to build upon the current science and move forward with carbon projects which ensure eff ective,long-term carbon sinks and maximize benefi ts for biodiversity and people;this is particularly important with a growing public and private interest in this fi eld.展开更多
External return mechanism is a mechanical structure applied to axial piston pumps.To study its lubrication characteristics,the Reynolds equation applied to an external return spherical hinge pair was deduced based on ...External return mechanism is a mechanical structure applied to axial piston pumps.To study its lubrication characteristics,the Reynolds equation applied to an external return spherical hinge pair was deduced based on the vector equation of relative-motion velocity of the external return spherical hinge pair under the influence of external swash plate inclination and offset distance.The results show that the total friction,axial leakage flow,and maximum value of the maximum oil-film pressure increase with increasing pump-shaft speed and decrease with increasing offset distance in one working cycle when the external-swash-plate inclination is constant.However,the varying offset distance has little effect on the axial leakage flow.The maximum value of the maximum oil-film pressure decreases with increasing external-swash-plate inclination and the total leakage flow increases with increasing external-swash-plate inclination in one working cycle when the offset distance is constant.It can be seen that the abovementioned parameters are important factors that affect the lubrication characteristics of external return spherical hinge pairs.Therefore,the complex effects of different coupling parameters should be comprehensively considered in the design of the external return mechanism.展开更多
The Moso bamboo,a renewable green building material used in various new green buildings,have received exten-sive attention with the promotion of the concept of green buildings.To explore the mechanical properties of M...The Moso bamboo,a renewable green building material used in various new green buildings,have received exten-sive attention with the promotion of the concept of green buildings.To explore the mechanical properties of Moso bamboo connections with external clamp steel plates,the 16 specimens were designed by changing the bolt diameters and the end distances of the bolt holes.Their static tension tests were conducted to investigate bearing capacities and failure modes of different connection configurations.Based on test results,three failure modes of these connections were obtained,including the shear failure of bolt shank,bearing failure of bolt hole and punch-ing shear failure of the Moso bamboo.The influence of bolt diameters and end distances of bolt holes on bearing capacities of the connections was quantitatively analyzed.Based on a simplified mechanical model,the analytical models were deduced for the bolt shear failure and the bearing failure of bolt holes.The results showed that the predictive values are in substantial agreement with the experimental results.Finally,the design and manufacturing suggestions are recommended for this Moso bamboo connections.展开更多
基金National Natural Science Foundation of China(No.50875243)
文摘A novel weft insertion mechanism named eccentric conjugate non-circular gear & crank-rocker & gears train weft insertion mechanism was proposed in order to better meet the requirements of rapier loom's weft insertion mechanism as well as reduce the manufacturing difficulty. Meanwhile, based on the working principle of this mechanism, kinematical mathematic models of this mechanism were established and an aided analysis and simulation software was compiled. The influences of eccentricity ratio, deformation coefficient, and other important parameters on the kinematics characteristics of this mechanism were analyzed by using the software. A group of preferable parameters which could meet the requirements of weft insertion technology were obtained by means of human-computer interactive optimization method. The maximum velocity, maximum acceleration, and variation of acceleration of this mechanism are smaller than those of the conjugate cam weft insertion mechanism applied on TT96 rapier loom under the conditions of the same unilateral total stroke of rapier head and the same rotary speed of loom spindle; meanwhile the other demands of weaving technology can be met by this novel weft insertion mechanism.
基金National Natural Science Foundation of China (No. 50875243)Zhejiang Technique Innovation Group of Modern Textile Machinery, China (No. 2009R50018)+1 种基金Foundation of Education Department of Zhejiang Province, China (No.Y201019088)Foundation of New Textile R& D Emphasised Laboratory of Zhejiang Province, China (No. 2009FZD004)
文摘In order to analyze the kinematic performances of elliptic-gear and crank-rocker(EGCR) beating-up mechanism, kinematic mathematic models of the mechanism were established, and an aided analysis and simulation software were compiled. This software can display the kinematic characteristics and simulation motion of the mechanism according to different parameters. It also supplies a platform for human-computer interaction. A group of satisfactory parameters were selected by the software. A test bed of EGCR beating-up mechanism was developed according to these parameters. The kinematic performances of the mechanism were verified by high-speed video tape recorder.
基金This project is supported by National Natural Science Foundation of China (No.50275054)Provincial Natural Science Foundation of Guangdong, China (No.020923)Provincial Science and Technology Key Project of Industry of Guangdong, China(No.2003C102013)High Level Construction Project of South China University of Technology, China(No.73056060).
文摘Difference of offset spinning with conventional symmetric spinning is analyzed. A 3D FEM model for offset tube neck-spinning is established and the spinning process is simulated by means of ANSYS software. Dynamic boundary and contact problems in simulation are solved. Transient stress distribution of contact area, transient strain distribution of nodes in typical section and strain distribution of the workpiece at last are attained, the place and the cause of crack are analyzed. Strain variation curves with time of offset spinning and conventional spinning are compared. It shows the mechanism difference between offset spinning and conventional spinning. In addition, simulation results show how strain distribution of typical section, thickness of some typical nodes, axial extension in left section and force of three rollers change with time. According to the study of the variation curve, material flow law along radial, tangential and axial direction is attained and the whole spinning process is studied. The simulation results discover that offset distance is the key to manufacture offset non-symmetric tube, and process parameters change with spinning angle. Experiment data really reflect different process parameters' influence on conventional symmetric and offset spinning force. Experiments accord well with simulation.
基金Item Sponsored by National Natural Science Foundation of China (50575155)National Tenth-Five Key Technologies Research and Development Program(ZZ01-13A-03-03-04)Shanxi Provincial Key Technologies Research and Development Program of China (2006031174)
文摘According to the revised Cailikefu's rolling shear force formula, motion path equation of spatial seven-bar path was built, and a mechanical model, with the new structural feature of negative offset, was thus successfully established for 2 800 mm heavy shear of some iron and steel company. Shear and bar forces of steel plate, before and after the adoption of negative offset structure, were analyzed, as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. It was found that the back-wall push force keeps large even at the time that the maximum rolling shear was obtained; meanwhile, back-wall push force is the most approximate to side forces when 60--100 mm of offset was adopted. Both theoretical results and onsite shear quality show that the negative offset plays an important role in ensuring the stability of pure rolling shear and keeping blade clearance constant.
基金Supported by the National tenth-five Key Technologies R&D Programme (ZZ01-13A-03-03-04) .
文摘According to revised Cailikefu’s rolling shear force formula,motion path equation of spatial seven-bar path is built,and mechanical model,with such new structural features as negative offset,is thus successfully established for 2 800 mm heavy shear of some Iron&Steel Company. Shear force and bar force of steel plate,before and after adoption of negative offset structure,are analyzed,as well as horizontal force component of mechanism that influences pure rolling shear and back-wall push force that keeps blade clearance. The discovery is that back-wall push force could be kept large enough at rolling start-up (i.e. the time that the maximum rolling shear produces),meanwhile,back-wall push force is the most approximate to side forces with adoption of 60 mm-100 mm offset. Theoretical results and on-site shear quality both indicate that new structural features such as negative offset plays an important role in ensuring pure rolling shear and keeping blade clearance constant,which provide an effective means to improve quality of steel plate.
文摘在电动汽车无线充电系统中,负载锂电池的充电过程为先恒流再恒压,因此,无线电能传输(wireless power transfer,WPT)系统需要同时具备实现双输出的能力,且在双输出状态之间进行平稳切换。基于此,分析双边LCC(inductor-capacitor-capacitor)拓扑实现与负载无关的恒流/恒压输出条件,给出参数设计方法。针对系统可能会随机在不同方向上出现位移的情况,采用了双向同轴平面线圈的结构,即原边线圈由内外2个沿相反方向绕制的线圈串联组成。通过仿真和实验验证了本文提出的电动汽车无线充电系统具备同时实现恒流/恒压输出的能力,且在多方向偏移工况下实现稳定输出。
基金funded by Zhejiang A&F University(POAU GR022067)China Green Carbon Foundation(PAFD GR015155)。
文摘Forest carbon offset(FCO)projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets.However,there are challenges and barriers to developing an FCO project,such as carbon leakage and cost-eff ectiveness.There have been few attempts to summarize and synthesize all types and aspects of existing challenges and possible solutions for FCO projects.This paper systematically reviews and discusses the current challenges involved in developing FCO projects,and then draws on the experience and lessons of existing projects to show how those challenges were addressed in world-leading voluntary carbon standards,namely the Verifi ed Carbon Standard,the American Carbon Registry,the Climate Action Reserve,and Plan Vivo.These voluntary markets have rich experience in FCO projects and are responsible for a signifi cant share of the market.From the 53 publications used in this analysis,three broad thematic categories of challenges emerged.These were related to methodology,socio-economic implications,and implementation.Methodological challenges,particularly additionality,permanence,and leakage,were the focus of 46%of the selected research papers,while socio-economic challenges,including transaction,social,and opportunity costs,were addressed by 35%.The remaining 19%of the research articles focused on implementational challenges related to monitoring,reporting,and verifi cation.Major voluntary standards adequately addressed most of the methodological and implementational barriers by adopting various approaches.However,the standards did not adequately address socio-economic issues,despite these being the second most frequently discussed theme in the papers analyzed.More research is clearly needed on the socio-economic challenges involved in the development of FCO projects.For the development of high-quality forestry carbon off set projects,there are many challenges and no simple,universal recipe for addressing them.However,it is crucial to build upon the current science and move forward with carbon projects which ensure eff ective,long-term carbon sinks and maximize benefi ts for biodiversity and people;this is particularly important with a growing public and private interest in this fi eld.
基金Project(GXXT-2019-048)supported by the University Synergy Innovation Program of Anhui Province,ChinaProject(51575002)supported by the National Natural Science Foundation of ChinaProject(gxbj ZD11)supported by the Top-Notch Talent Program of University(Profession)in Anhui Province,China。
文摘External return mechanism is a mechanical structure applied to axial piston pumps.To study its lubrication characteristics,the Reynolds equation applied to an external return spherical hinge pair was deduced based on the vector equation of relative-motion velocity of the external return spherical hinge pair under the influence of external swash plate inclination and offset distance.The results show that the total friction,axial leakage flow,and maximum value of the maximum oil-film pressure increase with increasing pump-shaft speed and decrease with increasing offset distance in one working cycle when the external-swash-plate inclination is constant.However,the varying offset distance has little effect on the axial leakage flow.The maximum value of the maximum oil-film pressure decreases with increasing external-swash-plate inclination and the total leakage flow increases with increasing external-swash-plate inclination in one working cycle when the offset distance is constant.It can be seen that the abovementioned parameters are important factors that affect the lubrication characteristics of external return spherical hinge pairs.Therefore,the complex effects of different coupling parameters should be comprehensively considered in the design of the external return mechanism.
基金The authors would like to appreciate the support from the Graduate Research and Innovation Foundation of Chongqing in China(Grant No.CYS20026)the National Key Research and Development Program of China(Grant No.2017YFC0703504).
文摘The Moso bamboo,a renewable green building material used in various new green buildings,have received exten-sive attention with the promotion of the concept of green buildings.To explore the mechanical properties of Moso bamboo connections with external clamp steel plates,the 16 specimens were designed by changing the bolt diameters and the end distances of the bolt holes.Their static tension tests were conducted to investigate bearing capacities and failure modes of different connection configurations.Based on test results,three failure modes of these connections were obtained,including the shear failure of bolt shank,bearing failure of bolt hole and punch-ing shear failure of the Moso bamboo.The influence of bolt diameters and end distances of bolt holes on bearing capacities of the connections was quantitatively analyzed.Based on a simplified mechanical model,the analytical models were deduced for the bolt shear failure and the bearing failure of bolt holes.The results showed that the predictive values are in substantial agreement with the experimental results.Finally,the design and manufacturing suggestions are recommended for this Moso bamboo connections.