In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three dimensional nonlinear flutter analysis, in which the nonlinearities of structural dy...In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long span suspension bridges during erection.展开更多
In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms( MAV) in full elevating domain,an auto-leveling mechanism for the platform is proposed based on a control metho...In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms( MAV) in full elevating domain,an auto-leveling mechanism for the platform is proposed based on a control method of booms-constraint,where mixed-boom structures and elevating characteristics are considered. Three models of constraint strategies include non-constraint model,elevating constraint model and lowering constraint model,which is designed to meet the leveling requirements in full working extent. Through the hydro-mechatronic unified modeling,a virtual prototype model is set up based on the auto-leveling mechanism,and leveling performances of the platform are studied during booms elevating to the maximum working height and extent. Simulation results show that the control method of booms-constraint can realize auto-leveling of the platform under two typical working conditions,meanwhile a leveling deviation appears at the constrained point,but the platform inclination is adjusted in the permissible range. The control method does not only restrict booms' freedom elevating to a certain extent,but also impacts the booms extending to the maximum working range. Experimental results verify that the auto-leveling mechanism based on booms-constraint control is valid and rational,which provides an effective technology approach for development of the platform leveling of MAV.展开更多
Objective To observe the clinical effects on spinal stenosis treated with acupuncture on Huatuo Jiaji （夹脊EX-B 2） and vertebral curvature adjustment. Methods Comprehensive therapy was applied to all of 189 cases of...Objective To observe the clinical effects on spinal stenosis treated with acupuncture on Huatuo Jiaji （夹脊EX-B 2） and vertebral curvature adjustment. Methods Comprehensive therapy was applied to all of 189 cases of any type of spinal stenosis, in which gukong needling technique was applied to Huatuo Jiaji （夹脊EX-B 2） at C4 - T5 and T12 - L5, associated with vertebral curvature adjustment with traction. The therapeutic effects were observed. Results Total effective rate was 96.8%, in which, clinical cured rate was 31.7% and excellent and good rate was 89.9% in average 28-month fol- low-up visit. Conclusion Spinal stenosis is segmental dynamic stenosis. It can be cured by acupuncture on Huatuo Jiaji （夹脊EX-B 2） and vertebral curvature adjustment and satisfactory result is achieved.展开更多
文摘In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long span suspension bridges during erection.
基金Supported by the National Natural Science Foundation of China(No.51509006)National Key Technology R&D Program(No.2015BAF07B08)Fundamental Research Funds for the Central Universities of Chang’an University(No.310825161008)
文摘In order to achieve an automatic leveling function for work platforms of aerial vehicles with mixed-booms( MAV) in full elevating domain,an auto-leveling mechanism for the platform is proposed based on a control method of booms-constraint,where mixed-boom structures and elevating characteristics are considered. Three models of constraint strategies include non-constraint model,elevating constraint model and lowering constraint model,which is designed to meet the leveling requirements in full working extent. Through the hydro-mechatronic unified modeling,a virtual prototype model is set up based on the auto-leveling mechanism,and leveling performances of the platform are studied during booms elevating to the maximum working height and extent. Simulation results show that the control method of booms-constraint can realize auto-leveling of the platform under two typical working conditions,meanwhile a leveling deviation appears at the constrained point,but the platform inclination is adjusted in the permissible range. The control method does not only restrict booms' freedom elevating to a certain extent,but also impacts the booms extending to the maximum working range. Experimental results verify that the auto-leveling mechanism based on booms-constraint control is valid and rational,which provides an effective technology approach for development of the platform leveling of MAV.
文摘Objective To observe the clinical effects on spinal stenosis treated with acupuncture on Huatuo Jiaji （夹脊EX-B 2） and vertebral curvature adjustment. Methods Comprehensive therapy was applied to all of 189 cases of any type of spinal stenosis, in which gukong needling technique was applied to Huatuo Jiaji （夹脊EX-B 2） at C4 - T5 and T12 - L5, associated with vertebral curvature adjustment with traction. The therapeutic effects were observed. Results Total effective rate was 96.8%, in which, clinical cured rate was 31.7% and excellent and good rate was 89.9% in average 28-month fol- low-up visit. Conclusion Spinal stenosis is segmental dynamic stenosis. It can be cured by acupuncture on Huatuo Jiaji （夹脊EX-B 2） and vertebral curvature adjustment and satisfactory result is achieved.
