The dynamic equations of motion of asymmetric offshore platforms under three different environmental conditions:seismic action,wave action and their combination are established in this paper. In establishing these mot...The dynamic equations of motion of asymmetric offshore platforms under three different environmental conditions:seismic action,wave action and their combination are established in this paper. In establishing these motion equations,three typical eccentricity types including mass eccentricity,rigidity eccentricity and their combination were considered,as are eccentricities that occur un-idirectionally and bi-directionally. The effects of the eccentricity type,the dynamic characteristics and the environmental conditions on the torsional coupling response of platforms are investigated and compared. An effort has also been made to analyze the inffluence of accidental eccentricity on asymmetric platforms with different eccentricity in two horizontally orthogonal directions. The results are given in terms of non-dimensional parameters,accounting for the uncoupled torsional to lateral frequency ratio. Numerical results reveal that the eccentricity type has a great inffluence on the torsionally coupled response under different environmental conditions. Therefore,it is necessary to consider the combination of earthquake and wave action in the seismic response analysis of some offshore platforms.展开更多
A novel asymmetrical pitch system for rotary wing is presented. The pitch control characteristics are studied and analyzed. Because elastic linkage is a key part in whole asymmetrical pitch system, in order to obtain ...A novel asymmetrical pitch system for rotary wing is presented. The pitch control characteristics are studied and analyzed. Because elastic linkage is a key part in whole asymmetrical pitch system, in order to obtain the variation of the elastic linkage deformation, an experimental platform mainly based on the device of micro aerial vehicles （MAVs） and a new control system mounted on TMS320LF2407 are designed. This control system has its compacted configuration and reliability. Finally, using this system to control the MAV for simulating the flying forward, experimental results show the MAV＇s flight attitude can he controlled based on the variation of the elastic linkage.展开更多
In contemporary society, the problem of information asymmetry in talent markets has been becoming more prominent. On one hand, the company and candidates fight against each other based on the information available, so...In contemporary society, the problem of information asymmetry in talent markets has been becoming more prominent. On one hand, the company and candidates fight against each other based on the information available, so both of them could make fraud that will make the market level lower and lower. On the other hand, former scholars have studied from enterprises＇ perspective and put forward methods to solve it based on the aspect of improving the technology and standard mechanism, which could not solve the problem of information asymmetry thoroughly. Consequently, this research put up with the idea that the market can reduce information asymmetry through the establishing personnel information database and related platforms, which has a great practical significance on realizing the optimal allocation of the market and saving cost. At the same time, this study discussed the problems of information asymmetry fundamentally, which was of great importance to enrich the related theory research. Specific models were constructed through two perspectives from the enterprise and the candidates. And then two models would be eventually integrated into a large system. Finally, this research put all related information into a system, which was beneficial to the optimal allocation of human resources with constraints of the market environment.展开更多
为解决弯扭耦合复合材料薄壁叶片的发散不稳定问题,阐述了风力机叶片准稳态响应及基于回路传输恢复的LQG(LQG with Loop Transfer Recovery,LLTR)理论控制过程。叶片结构模型是基于周向反对称刚度铺层的复合材料薄壁单闭室翼型;翼型的...为解决弯扭耦合复合材料薄壁叶片的发散不稳定问题,阐述了风力机叶片准稳态响应及基于回路传输恢复的LQG(LQG with Loop Transfer Recovery,LLTR)理论控制过程。叶片结构模型是基于周向反对称刚度铺层的复合材料薄壁单闭室翼型;翼型的中线轨迹是S809Ⅱ翼型型线。从直升机叶片的失速气动力模型中提取了一种准稳态气动力模型,经过修正后适合于风力机叶片经典颤振和失速颤振临界状态的研究。分别详细研究了基于输入端回路传输恢复及输出端回路传输恢复两种情况下的LLTR控制,并通过弯扭时域响应和控制器响应的数字仿真比较以及奇异值伯德图曲线对比,论证了LLTR控制算法的稳定性及在颤振抑制方面的优越性。控制算法的实时效应也通过半实物仿真实验平台得到了检验。展开更多
基金Program for Chang Kong Scholars and Innovative Research Team (No.IRT0518)National Natural Science Foundation of China Under Grant No.50708013
文摘The dynamic equations of motion of asymmetric offshore platforms under three different environmental conditions:seismic action,wave action and their combination are established in this paper. In establishing these motion equations,three typical eccentricity types including mass eccentricity,rigidity eccentricity and their combination were considered,as are eccentricities that occur un-idirectionally and bi-directionally. The effects of the eccentricity type,the dynamic characteristics and the environmental conditions on the torsional coupling response of platforms are investigated and compared. An effort has also been made to analyze the inffluence of accidental eccentricity on asymmetric platforms with different eccentricity in two horizontally orthogonal directions. The results are given in terms of non-dimensional parameters,accounting for the uncoupled torsional to lateral frequency ratio. Numerical results reveal that the eccentricity type has a great inffluence on the torsionally coupled response under different environmental conditions. Therefore,it is necessary to consider the combination of earthquake and wave action in the seismic response analysis of some offshore platforms.
基金supported by the National Natural Science Foundation of China (Grant No.60605028)the National High-Technology Research and Development Program of China (Grant No.2007AA04Z225)+2 种基金the Shanghai Rising-Star Program (Grant Nos.07QA14024, 07QH14006)the Shanghai Shuguang Program (Grant No.07SG47)the Shanghai Leading Key Laboratory of Mechanical Automation and Robotics Science Foundation (Grant No.ZZ0805)
文摘A novel asymmetrical pitch system for rotary wing is presented. The pitch control characteristics are studied and analyzed. Because elastic linkage is a key part in whole asymmetrical pitch system, in order to obtain the variation of the elastic linkage deformation, an experimental platform mainly based on the device of micro aerial vehicles （MAVs） and a new control system mounted on TMS320LF2407 are designed. This control system has its compacted configuration and reliability. Finally, using this system to control the MAV for simulating the flying forward, experimental results show the MAV＇s flight attitude can he controlled based on the variation of the elastic linkage.
文摘In contemporary society, the problem of information asymmetry in talent markets has been becoming more prominent. On one hand, the company and candidates fight against each other based on the information available, so both of them could make fraud that will make the market level lower and lower. On the other hand, former scholars have studied from enterprises＇ perspective and put forward methods to solve it based on the aspect of improving the technology and standard mechanism, which could not solve the problem of information asymmetry thoroughly. Consequently, this research put up with the idea that the market can reduce information asymmetry through the establishing personnel information database and related platforms, which has a great practical significance on realizing the optimal allocation of the market and saving cost. At the same time, this study discussed the problems of information asymmetry fundamentally, which was of great importance to enrich the related theory research. Specific models were constructed through two perspectives from the enterprise and the candidates. And then two models would be eventually integrated into a large system. Finally, this research put all related information into a system, which was beneficial to the optimal allocation of human resources with constraints of the market environment.
文摘为解决弯扭耦合复合材料薄壁叶片的发散不稳定问题,阐述了风力机叶片准稳态响应及基于回路传输恢复的LQG(LQG with Loop Transfer Recovery,LLTR)理论控制过程。叶片结构模型是基于周向反对称刚度铺层的复合材料薄壁单闭室翼型;翼型的中线轨迹是S809Ⅱ翼型型线。从直升机叶片的失速气动力模型中提取了一种准稳态气动力模型,经过修正后适合于风力机叶片经典颤振和失速颤振临界状态的研究。分别详细研究了基于输入端回路传输恢复及输出端回路传输恢复两种情况下的LLTR控制,并通过弯扭时域响应和控制器响应的数字仿真比较以及奇异值伯德图曲线对比,论证了LLTR控制算法的稳定性及在颤振抑制方面的优越性。控制算法的实时效应也通过半实物仿真实验平台得到了检验。
