The coordination abilities are closely related to the development of technical motor skills, where the player cannot master the technical skills in the special activity, in case lack of special coordination abilities ...The coordination abilities are closely related to the development of technical motor skills, where the player cannot master the technical skills in the special activity, in case lack of special coordination abilities for this activity. Many of table tennis experts agree on that the special coordination abilities for table tennis include each of： （1） the motor adaptation and adjustment ability; （2） the ability to differentiate; （3） reaction speed ability; （4） orientation ability; （5） balance ability; （6） coupling ability; and （7） the ability to sense the rhythm. The aim of this study is to design a training program to develop the special coordination abilities of table tennis and identify the impact of this program on the general skill ability for table tennis juniors. The researcher used the experimental method in two groups： One group is experimental group and another is the control group. The most important result of this study was the training program led to the improvement of the special coordination abilities of table tennis for the experimental group, which led to higher levels of the general skill ability in table tennis for the experimental group more than the control group.展开更多
In order to evaluate the seismic behavior of confined RC column-composite beam joints, five interior joints were tested under low cyclic reversed load. The weakening extent of flanges, the number of studs, and whether...In order to evaluate the seismic behavior of confined RC column-composite beam joints, five interior joints were tested under low cyclic reversed load. The weakening extent of flanges, the number of studs, and whether to reinforce weakened flanges were used as parameters in designing these five joints. Failure characteristics, hysteretic curves, skeleton curves, ductility, energy dissipation, strength degradation, and stiffness degradation were analyzed. The test results revealed that the steel beam flanges in the joints were equivalent to the tie rod. Weakened flanges resulted in poor seismic behavior; however, the seismic behavior could be improved by increasing studs and reinforcing weakened flanges. The joint steel plate hoops, equivalent to stirrups, did not yield when the maximum load was reached, but yielded when the failure load was reached for the joints with shear failure. Increasing stud-type joints and reinforcing flange-type joints ensured good seismic behavior and met project requirements. Based on the experimental results, the failure mechanism of the joints was discussed, and the shear capacity equations of the joints was presented.展开更多
In the Raymond mill grinding processes,high-accuracy control for the current of Raymond mill is vital to enhance the product quality and production efficiency as well as cut down the consumption of spare parts.However...In the Raymond mill grinding processes,high-accuracy control for the current of Raymond mill is vital to enhance the product quality and production efficiency as well as cut down the consumption of spare parts.However,strong external disturbances,such as variations of ore hardness and ore size,always exist.It is not easy to make the current of Raymond mill constant due to these strong disturbances.Several control strategies have been proposed to control the grinding processes.However,most of them(such as PID and MPC)reject disturbances merely through feedback regulation and do not deal with the disturbances directly,which may lead to poor control performance when strong disturbances occur.To improve disturbance rejection performance,a control scheme based on PI and disturbance observer is proposed in this work.The scheme combines a feedforward compensation part based on disturbance observer and a feedback regulation part using PI.The test results illustrate that the proposed method can obtain remarkable superiority in disturbance rejection compared with PI method in the Raymond mill grinding processes.展开更多
文摘The coordination abilities are closely related to the development of technical motor skills, where the player cannot master the technical skills in the special activity, in case lack of special coordination abilities for this activity. Many of table tennis experts agree on that the special coordination abilities for table tennis include each of： （1） the motor adaptation and adjustment ability; （2） the ability to differentiate; （3） reaction speed ability; （4） orientation ability; （5） balance ability; （6） coupling ability; and （7） the ability to sense the rhythm. The aim of this study is to design a training program to develop the special coordination abilities of table tennis and identify the impact of this program on the general skill ability for table tennis juniors. The researcher used the experimental method in two groups： One group is experimental group and another is the control group. The most important result of this study was the training program led to the improvement of the special coordination abilities of table tennis for the experimental group, which led to higher levels of the general skill ability in table tennis for the experimental group more than the control group.
基金Supported by the National Natural Science Foundation of China(No.51209094)
文摘In order to evaluate the seismic behavior of confined RC column-composite beam joints, five interior joints were tested under low cyclic reversed load. The weakening extent of flanges, the number of studs, and whether to reinforce weakened flanges were used as parameters in designing these five joints. Failure characteristics, hysteretic curves, skeleton curves, ductility, energy dissipation, strength degradation, and stiffness degradation were analyzed. The test results revealed that the steel beam flanges in the joints were equivalent to the tie rod. Weakened flanges resulted in poor seismic behavior; however, the seismic behavior could be improved by increasing studs and reinforcing weakened flanges. The joint steel plate hoops, equivalent to stirrups, did not yield when the maximum load was reached, but yielded when the failure load was reached for the joints with shear failure. Increasing stud-type joints and reinforcing flange-type joints ensured good seismic behavior and met project requirements. Based on the experimental results, the failure mechanism of the joints was discussed, and the shear capacity equations of the joints was presented.
基金Projects(61504027,61573099)supported by the National Natural Science Foundation of ChinaProject(BK20140647)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘In the Raymond mill grinding processes,high-accuracy control for the current of Raymond mill is vital to enhance the product quality and production efficiency as well as cut down the consumption of spare parts.However,strong external disturbances,such as variations of ore hardness and ore size,always exist.It is not easy to make the current of Raymond mill constant due to these strong disturbances.Several control strategies have been proposed to control the grinding processes.However,most of them(such as PID and MPC)reject disturbances merely through feedback regulation and do not deal with the disturbances directly,which may lead to poor control performance when strong disturbances occur.To improve disturbance rejection performance,a control scheme based on PI and disturbance observer is proposed in this work.The scheme combines a feedforward compensation part based on disturbance observer and a feedback regulation part using PI.The test results illustrate that the proposed method can obtain remarkable superiority in disturbance rejection compared with PI method in the Raymond mill grinding processes.
