Currently, transplanting mechanisms for dryland plug seedlings in China are mainly semiautomatic and have low efficiency. The rotary seedling pick-up mechanism with a planetary gear train for non-uniform intermittent ...Currently, transplanting mechanisms for dryland plug seedlings in China are mainly semiautomatic and have low efficiency. The rotary seedling pick-up mechanism with a planetary gear train for non-uniform intermittent transmission, and a concave and convex locking arc device, has a large rigid impact. To solve these problems, according to the design requirements for a dryland plug seedling transplanting mechanism, a rotary seedling pick-up mechanism of a planetary gear train with combined non-circular gear transmission of incomplete eccentric circular and noncircular gears was proposed. This has the characteristics of two-times greater fluctuation of the transmission ratio in a cycle, and can achieve a non-uniform continuous drive. Through analysis of the working principle of the seedling pick-up mechanism, its kinematics model was established. The human–computer interaction optimization method and self-developed computer-aided analysis and optimization software were used to obtain a set of parameters that satisfy the operation requirements of the seedling pick-up mechanism. According to the optimized parameters, the structure of the seedling pick-up mechanism was designed, a virtual prototype of the mechanism was created, and a physical prototype was manufactured. A virtual motion simulation of the mechanism was performed, high-speed photographic kinematics tests were conducted, and the kinematic properties of the physical prototype were investigated, whereby the correctness of the theoretical model and the optimized design of the mechanism were verified. Further, laboratory seedling pick-up tests were conducted. The success ratio of seedling pick-up was 93.8% when the seedling pick-up efficiency of the mechanism was 60 plants per minute per row, indicating that the mechanism has a high efficiency and success ratio for seedling pick-up and can be applied to a dryland plug seedling transplanter.展开更多
Objective: The purpose of this study was to compare long-term stability and satisfaction between orthodontic camouflage and orthognathic surgery in treatment of moderate skeletal Class III adults. Materials and Method...Objective: The purpose of this study was to compare long-term stability and satisfaction between orthodontic camouflage and orthognathic surgery in treatment of moderate skeletal Class III adults. Materials and Methods: A total of 25 adults females who had been treated with orthodontic camouflage for Class III malocclusions were recalled at least 3 years post-treatment to evaluate stability and satisfaction with treatment outcomes. The data were compared with similar data for long-term outcomes in 21 patients with the same Class III problems who had bimaxillary surgical correction. Results: In the camouflage patients, small mean changes in skeletal landmark positions occurred over the long term, although the changes were generally much smaller than in the surgery patients. Dental changes in the surgery group were more severe than those in the camouflage group. The camouflage patients reported fewer functional or temporomandibular joint problems than did the surgery patients. Both groups reported similar levels of overall satisfaction with treatment. Conclusion: The results suggest that both camouflage and surgical treatment in moderate skeletal Class III adults can achieve satisfactory outcomes and provide long-term stability. If patients do not readily accept surgery because of potential surgical complications or financial difficulties, camouflage treatment may be an effective alternative treatment.展开更多
Information recording on paper has always been the most important approach to keep records of human activity and to spread civilization.With the progress of science and technology,paper with different functions should...Information recording on paper has always been the most important approach to keep records of human activity and to spread civilization.With the progress of science and technology,paper with different functions should be exploited to conform to the increasing demands in various scenarios.In one aspect,traditional paper can only be used once,and using large amounts of paper causes deforestation,additional solid waste treatment,environmental pollution,and high energy consumption.Consequently,the development of rewritable paper that is environment-friendly,low cost,and can save resources is significant for green printing.In the other aspect,information leakage brings security issues,which may lead to severe consequences,such as war outbreak,economic loss,social problems,and so on.Therefore,the development of security printing has also attracted wide interests.Stimuli-responsive photofunctional materials that have reversible variations in absorption or emission in response to changes in the external environmental have a great potential for the achievement of green and security printing.To date,much progress has been made in these research areas.This paper lists different smart materials that respond to various external stimuli,such as light,water,pH,heat,and metal ions,and summarizes the recent advances towards green and security printing.Also,we discuss the current challenges and future directions in this rapidly growing research field.It is expected that this review article will stimulate and guide future studies for the advanced green and security printing.展开更多
To design a clamping-pot-type wide-narrow-row pot seedling transplanting(WPST)mechanism with desired spatial beak-shaped trajectory and working posture,a new design method of planetary gear train transplanting mechani...To design a clamping-pot-type wide-narrow-row pot seedling transplanting(WPST)mechanism with desired spatial beak-shaped trajectory and working posture,a new design method of planetary gear train transplanting mechanism(PGTM)with non-circular gears based on several key spatial poses(position and posture)was proposed.The PGTM was simplified to a spatial open-loop chain with two-revolute(2R)joints.The geometric constraint equations containing only the structural parameters of the chain were then established on the basis of the three key spatial poses,and the homotopy algorithm was used to obtain all the required parameters of the mechanism.In accordance with the parameters obtained,the relative angular displacement relation between the planet carrier and the transplanting arm was optimized,the trajectory of the mechanism was replayed,and the total transmission ratio was determined.The degree of freedom of the spatial 2R mechanism was reduced by attaching to the unequal gear pair,and the transmission ratio was distributed in accordance with the gear type to realize the design of a non-circular gear pitch curve.Lastly,a clamping-pot-type PGTM for rice WPST driven by the combination of planar non-circular and non-conical gears was designed,and virtual simulation and prototype test were conducted.Results showed that the simulation and prototype test trajectories were consistent with the desired trajectory.Under the operating speeds of 50 r/min and 90 r/min,the success rates of seedling picking were 95.32%and 90.15%,respectively,which verified the feasibility of the theoretical method.This method could provide a reference for the design of a spatial PGTM with nonuniform transmission.展开更多
基金Supported by National Key Research and Development Program of China(Project No.2017YFD0700800)Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ16E050003)+1 种基金Natural Science Foundation of China(Grant No.51505429)Science Foundation of Zhejiang Sci-Tech University(Grant No.15022011-Y)
文摘Currently, transplanting mechanisms for dryland plug seedlings in China are mainly semiautomatic and have low efficiency. The rotary seedling pick-up mechanism with a planetary gear train for non-uniform intermittent transmission, and a concave and convex locking arc device, has a large rigid impact. To solve these problems, according to the design requirements for a dryland plug seedling transplanting mechanism, a rotary seedling pick-up mechanism of a planetary gear train with combined non-circular gear transmission of incomplete eccentric circular and noncircular gears was proposed. This has the characteristics of two-times greater fluctuation of the transmission ratio in a cycle, and can achieve a non-uniform continuous drive. Through analysis of the working principle of the seedling pick-up mechanism, its kinematics model was established. The human–computer interaction optimization method and self-developed computer-aided analysis and optimization software were used to obtain a set of parameters that satisfy the operation requirements of the seedling pick-up mechanism. According to the optimized parameters, the structure of the seedling pick-up mechanism was designed, a virtual prototype of the mechanism was created, and a physical prototype was manufactured. A virtual motion simulation of the mechanism was performed, high-speed photographic kinematics tests were conducted, and the kinematic properties of the physical prototype were investigated, whereby the correctness of the theoretical model and the optimized design of the mechanism were verified. Further, laboratory seedling pick-up tests were conducted. The success ratio of seedling pick-up was 93.8% when the seedling pick-up efficiency of the mechanism was 60 plants per minute per row, indicating that the mechanism has a high efficiency and success ratio for seedling pick-up and can be applied to a dryland plug seedling transplanter.
文摘Objective: The purpose of this study was to compare long-term stability and satisfaction between orthodontic camouflage and orthognathic surgery in treatment of moderate skeletal Class III adults. Materials and Methods: A total of 25 adults females who had been treated with orthodontic camouflage for Class III malocclusions were recalled at least 3 years post-treatment to evaluate stability and satisfaction with treatment outcomes. The data were compared with similar data for long-term outcomes in 21 patients with the same Class III problems who had bimaxillary surgical correction. Results: In the camouflage patients, small mean changes in skeletal landmark positions occurred over the long term, although the changes were generally much smaller than in the surgery patients. Dental changes in the surgery group were more severe than those in the camouflage group. The camouflage patients reported fewer functional or temporomandibular joint problems than did the surgery patients. Both groups reported similar levels of overall satisfaction with treatment. Conclusion: The results suggest that both camouflage and surgical treatment in moderate skeletal Class III adults can achieve satisfactory outcomes and provide long-term stability. If patients do not readily accept surgery because of potential surgical complications or financial difficulties, camouflage treatment may be an effective alternative treatment.
基金National Funds for Distinguished Young Scientists,Grant/Award Number:61825503National Natural Science Foundation of China,Grant/Award Numbers:21701087,61775101Priority Academic Program Development of Jiangsu Higher Education Institutions,Grant/Award Number:YX030003。
文摘Information recording on paper has always been the most important approach to keep records of human activity and to spread civilization.With the progress of science and technology,paper with different functions should be exploited to conform to the increasing demands in various scenarios.In one aspect,traditional paper can only be used once,and using large amounts of paper causes deforestation,additional solid waste treatment,environmental pollution,and high energy consumption.Consequently,the development of rewritable paper that is environment-friendly,low cost,and can save resources is significant for green printing.In the other aspect,information leakage brings security issues,which may lead to severe consequences,such as war outbreak,economic loss,social problems,and so on.Therefore,the development of security printing has also attracted wide interests.Stimuli-responsive photofunctional materials that have reversible variations in absorption or emission in response to changes in the external environmental have a great potential for the achievement of green and security printing.To date,much progress has been made in these research areas.This paper lists different smart materials that respond to various external stimuli,such as light,water,pH,heat,and metal ions,and summarizes the recent advances towards green and security printing.Also,we discuss the current challenges and future directions in this rapidly growing research field.It is expected that this review article will stimulate and guide future studies for the advanced green and security printing.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFD0700703)the National Natural Science Foundation of China(Grant No.51975534,51675487)+2 种基金the Zhejiang Provincial Key Research and Development Program(Grant No.2018C02046)the Natural Science Foundation of Zhejiang Province(Grant No.LY19E050021)the 151 Talent Plan of Zhejiang Province,and the Project of Zhejiang Provincial Young and Middle-aged Discipline Leaders.
文摘To design a clamping-pot-type wide-narrow-row pot seedling transplanting(WPST)mechanism with desired spatial beak-shaped trajectory and working posture,a new design method of planetary gear train transplanting mechanism(PGTM)with non-circular gears based on several key spatial poses(position and posture)was proposed.The PGTM was simplified to a spatial open-loop chain with two-revolute(2R)joints.The geometric constraint equations containing only the structural parameters of the chain were then established on the basis of the three key spatial poses,and the homotopy algorithm was used to obtain all the required parameters of the mechanism.In accordance with the parameters obtained,the relative angular displacement relation between the planet carrier and the transplanting arm was optimized,the trajectory of the mechanism was replayed,and the total transmission ratio was determined.The degree of freedom of the spatial 2R mechanism was reduced by attaching to the unequal gear pair,and the transmission ratio was distributed in accordance with the gear type to realize the design of a non-circular gear pitch curve.Lastly,a clamping-pot-type PGTM for rice WPST driven by the combination of planar non-circular and non-conical gears was designed,and virtual simulation and prototype test were conducted.Results showed that the simulation and prototype test trajectories were consistent with the desired trajectory.Under the operating speeds of 50 r/min and 90 r/min,the success rates of seedling picking were 95.32%and 90.15%,respectively,which verified the feasibility of the theoretical method.This method could provide a reference for the design of a spatial PGTM with nonuniform transmission.
