The clearances appear in chain link hinges induced by manufacturing tolerance or wear of components are the most important factor that influences the dynamic performance of the intermittent roller chain drives. Due to...The clearances appear in chain link hinges induced by manufacturing tolerance or wear of components are the most important factor that influences the dynamic performance of the intermittent roller chain drives. Due to the existence of the clearances in chain link hinges, the serious impact vibration phenomenon which influences the stability and the position accuracy of the chain drive system would be caused in the intermittent motion. But, the problem may be that a reasonable modeling on the chain with clearances is difficult due to the large clearance＇s number in chain system and the fact that the clearance＇ size are different. Currently, the studies on the dynamics of the intermittent roller chain considering the multi-clearance＇ joints are rare. Most research works have only focused on the constant moving chains. Taking the intermittent roller chain system as an object, this paper designs and builds the experimental device of this kind of mechanical system. The Longitudinal vibration response of the intermittent chain under the different motion laws was tested. The experimental study shows that the clearances presented in chain link hinges can cause severe impact vibration in the intermittent motion of chain. In subsequent work, the dynamic model of the intermittent roller chain system with the multi-clearance＇ joints was established. By calculating the dynamic response of this kind of mechanical system under the different motion laws, the effect of the clearances on the dynamic response of the intermittent chain drive system was analyzed. The theoretical simulation shows that the serious impact vibration phenomenon of the chain system can be caused by the clearances at the start accelerating period, and the chain drive system is often accompanied by the severe shock and vibration at the moment that the chain moves from the acceleration period to deceleration period. The research conclusions made by the experimental and theoretical studies indicate that the use of motion laws with small and continuous 展开更多
AIM: To delineate the characteristics of the dynamic stereopsis test and analyze related parameters in intermittent exotropia [X(T)] patients. METHODS: Fifty-seven X(T) patients and 55 normal subjects were enrolled in...AIM: To delineate the characteristics of the dynamic stereopsis test and analyze related parameters in intermittent exotropia [X(T)] patients. METHODS: Fifty-seven X(T) patients and 55 normal subjects were enrolled in this study. The normal and X(T) groups were used to test the reproducibility and reliability of the dynamic stereopsis test, and Bangerter filters with densities of 0.2 were then used to simulate suppression to test for traditional and dynamic stereopsis. In the X(T) group, the measurements included 1) dynamic stereopsis test comprising three parts: motion+disparity, motion only and disparity only; 2) ocular deviation angle; 3) Bagolini striated lens test; 4) disease course; and 5) Titmus stereopsis test. RESULTS: The test-retest reliability of the dynamic stereopsis method was 0.901 in the normal and X(T) groups, and none of the X(T) patients were able to pass the static and dynamic stereopsis tests after using the 0.2 Bangerter filter. The accuracy rate was greater than 80% in the normal group and 31.81%, 36.36%, and 45.45% for the motion+disparity, motion-only and disparityonly components of the traditional test for X(T) patients diagnosed with stereoblindness via traditional tests,respectively. Patients with a long disease course(>1 y) had worse dynamic stereopsis than those with a short disease course(<1 y; P<0.05, Chi-square test). The deviation angle was not correlated with the motion+disparity, disparityonly, or the motion-only test components(all P>0.05, Chisquare test). CONCLUSION: Dynamic stereopsis is preserved in certain X(T) patients diagnosed with stereoblindness via traditional tests. A long disease course was shown to be a negative factor for dynamic stereopsis in X(T) patients which might be associated with worse progression, and provide good references clinically.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 50605060)Tianjin Municipal Natural Science Foundation of China (Grant No. 06YFJMJC03300)
文摘The clearances appear in chain link hinges induced by manufacturing tolerance or wear of components are the most important factor that influences the dynamic performance of the intermittent roller chain drives. Due to the existence of the clearances in chain link hinges, the serious impact vibration phenomenon which influences the stability and the position accuracy of the chain drive system would be caused in the intermittent motion. But, the problem may be that a reasonable modeling on the chain with clearances is difficult due to the large clearance＇s number in chain system and the fact that the clearance＇ size are different. Currently, the studies on the dynamics of the intermittent roller chain considering the multi-clearance＇ joints are rare. Most research works have only focused on the constant moving chains. Taking the intermittent roller chain system as an object, this paper designs and builds the experimental device of this kind of mechanical system. The Longitudinal vibration response of the intermittent chain under the different motion laws was tested. The experimental study shows that the clearances presented in chain link hinges can cause severe impact vibration in the intermittent motion of chain. In subsequent work, the dynamic model of the intermittent roller chain system with the multi-clearance＇ joints was established. By calculating the dynamic response of this kind of mechanical system under the different motion laws, the effect of the clearances on the dynamic response of the intermittent chain drive system was analyzed. The theoretical simulation shows that the serious impact vibration phenomenon of the chain system can be caused by the clearances at the start accelerating period, and the chain drive system is often accompanied by the severe shock and vibration at the moment that the chain moves from the acceleration period to deceleration period. The research conclusions made by the experimental and theoretical studies indicate that the use of motion laws with small and continuous
基金Supported by National Natural Science Foundation of China (No.81600761)the Natural Science Foundation Team Projectof Guangdong Province (No.2015A030312016)
文摘AIM: To delineate the characteristics of the dynamic stereopsis test and analyze related parameters in intermittent exotropia [X(T)] patients. METHODS: Fifty-seven X(T) patients and 55 normal subjects were enrolled in this study. The normal and X(T) groups were used to test the reproducibility and reliability of the dynamic stereopsis test, and Bangerter filters with densities of 0.2 were then used to simulate suppression to test for traditional and dynamic stereopsis. In the X(T) group, the measurements included 1) dynamic stereopsis test comprising three parts: motion+disparity, motion only and disparity only; 2) ocular deviation angle; 3) Bagolini striated lens test; 4) disease course; and 5) Titmus stereopsis test. RESULTS: The test-retest reliability of the dynamic stereopsis method was 0.901 in the normal and X(T) groups, and none of the X(T) patients were able to pass the static and dynamic stereopsis tests after using the 0.2 Bangerter filter. The accuracy rate was greater than 80% in the normal group and 31.81%, 36.36%, and 45.45% for the motion+disparity, motion-only and disparityonly components of the traditional test for X(T) patients diagnosed with stereoblindness via traditional tests,respectively. Patients with a long disease course(>1 y) had worse dynamic stereopsis than those with a short disease course(<1 y; P<0.05, Chi-square test). The deviation angle was not correlated with the motion+disparity, disparityonly, or the motion-only test components(all P>0.05, Chisquare test). CONCLUSION: Dynamic stereopsis is preserved in certain X(T) patients diagnosed with stereoblindness via traditional tests. A long disease course was shown to be a negative factor for dynamic stereopsis in X(T) patients which might be associated with worse progression, and provide good references clinically.
