Study on Rigid-Flexible Coupling Effects of Floating Offshore Wind Turbines

In order to account for rigid-flexible coupling effects of floating offshore wind turbines, a nonlinear rigid-flexible coupled dynamic model is proposed in this paper. The proposed nonlinear coupled model takes the higher-order axial displacements into account, which are usually neglected in the conventional linear dynamic model. Subsequently,investigations on the dynamic differences between the proposed nonlinear dynamic model and the linear one are conducted. The results demonstrate that the stiffness of the turbine blades in the proposed nonlinear dynamic model increases with larger overall motions but that in the linear dynamic model declines with larger overall motions.Deformation of the blades in the nonlinear dynamic model is more reasonable than that in the linear model as well.Additionally, more distinct coupling effects are observed in the proposed nonlinear model than those in the linear model. Finally, it shows that the aerodynamic loads, the structural loads and global dynamic responses of floating offshore wind turbines using the nonlinear dynamic model are slightly smaller than those using the linear dynamic model. In summary, compared with the conventional linear dynamic model, the proposed nonlinear coupling dynamic model is a higher-order dynamic model in consideration of the rigid-flexible coupling effects of floating offshore wind turbines, and accord more perfectly with the engineering facts.

聚·流·知·行——文化遗产再生之道

通过对美国马丁住宅保护案例分析,探讨在现有条件下我们应当如何发展行之有效的文化遗产保护模式。文章指出,即便在产权普遍私有的西方,重要历史建筑的保护和再生,仅靠各级政府或私人业主的力量也是行不通的。马丁住宅保护的成功,是有识人士广泛调动社会资源,集聚智慧,鼓励社区居民积极参与的结果。针对当前历史建筑保护所面临的制度建设滞后和资金短缺等问题进行讨论,作者提出文化遗产保护"聚·流·知·行"运作模式,建议参照目前业已得到一定发展的民间慈善事业,通过鼓励有识之士组织历史保护社会公益志愿者团体,拓宽筹资和公众参与渠道,实现专业知识融贯于保护实践等举措,来使文化遗产得到更为有效的管理、保护与再生。

张力腿式浮式风机耦合动力响应理论模型与数值实现

针对张力腿结构动力响应特点,提出一套张力腿式浮式风机动力耦合理论模型,编制计算程序,并通过与实验结果的对比,验证理论模型以及程序的适用性。张力腿式系泊系统稳定性好,但张力载荷随平台位移的变化显著;张力腿结构的动态响应与支撑平台和风机系统动态响应存在显著的耦合作用。针对张力腿浮式风机动力耦合特性,采用谱方法对张力腿结构建立耦合动力模型;考虑细长体在波浪中受到的粘性力,通过哈密顿原理推导出张力腿运动控制方程,利用自主开发的计算程序DARwind和数值计算方法求解系统动态响应。最后,将数值计算结果同UMAINE的试验数据进行对比分析,以验证程序的合理性。

Simulation annealing diagnosis algorithm method for optimized forecast of the dynamic response of floating offshore wind turbines

Design of floating offshore wind turbines(FOWTs)needs reliable and innovative technologies to overcome the challenges on how to better predict the dynamic responses in terms of aero-hydro-servo-elastic disciplines.This paper aims to demonstrate the optimized prediction of the dynamic response of FOWTs by Simulation annealing diagnosis algorithm(SADA).SADA is an Artificial Intelligence technology-based method,which utilizes the advantages of numerical simulation,basin experiment and machine learning algorithms.The actor network in deep deterministic policy gradient(DDPG)is adopted to take actions to adjust the Key disciplinary parameters(KDPs)in each loop according to the feedback of 6DOF motions of platform in dynamic response analysis.The results demonstrated that the mean values of the platform's motions and rotor axial thrust force could be predicted with higher accuracy.On this basis,other physical quantities that designers are more concerned about but cannot be obtained from experiments and actual measurements will be predicted by SADA with more credibility.This SADA method differs from traditional supervised learning applications in renewable energy,which do not need to be provided physical quantities with strong direct correlation.All targets can be artificially set for SADA to obtain a better self-learning performance.In general,designers can use SADA to get a more accurate and optimized prediction of the dynamic response of FOWTs,especially those physical quantities that cannot be directly obtained through the basin experiments.